Getting Started with AssemblyScript

WebAssembly (or Wasm) is a relatively recent addition to web browsers, but it has the potential to drastically expand what the web is capable of as a platform for serving applications.

While there can be a steep learning curve for web developers to get started with WebAssembly, AssemblyScript provides a way to get around that. Let’s first take a look at why WebAssembly is such a promising technology, and then we’ll see how AssemblyScript can help to unlock its potential.

WebAssembly

WebAssembly is a low-level language for browsers, giving developers a compilation target for the web besides JavaScript. It makes it possible for website code to run at near-native speed in a safe, sandboxed environment.

It was developed with input from representatives of all the major browsers (Chrome, Firefox, Safari, and Edge), who reached a design consensus in early 2017. All of these browsers now support WebAssembly, which is usable in about 87 percent of all browsers.

WebAssembly is delivered in a binary format, which means that it has both size and load time advantages over JavaScript. Yet it also has a textual representation that is human-readable.

When WebAssembly was first announced, some developers thought it had the potential to eventually supplant JavaScript as the primary language of the web. But it’s better to think of WebAssembly as a new tool that integrates well with the existing web platform, which is one of its high-level goals.

Rather than replacing JavaScript for existing use cases, WebAssembly is intriguing more because it enables new use cases. WebAssembly doesn’t have direct access to the DOM yet, and most existing websites will want to stick with JavaScript, which is already quite fast after going through years of optimization. Here’s a sample of WebAssembly’s own list of possible use cases:

  • Games
  • Scientific visualization and simulation
  • CAD applications
  • Image/video editing

The common attribute among these applications is that we would typically think of them as desktop applications. By providing near-native performance for CPU-intensive tasks, WebAssembly makes it feasible to move more of these applications to the web.

Existing websites can also benefit from WebAssembly. Figma provides a real-world example, having used WebAssembly to significantly improve their load time. If a website uses code that does a lot of computation, it can make sense to replace only that code with WebAssembly to improve performance.

So maybe now you’re interested in getting started with WebAssembly. You could learn the language itself and write it directly, but it was really intended to be a compilation target for other languages. It was designed to have good support for C and C++, Go added experimental support for it in version 1.11, and Rust is also investing heavily in it.

But maybe you don’t want to learn or use one of these languages in order to use WebAssembly. This is where AssemblyScript comes into play.

AssemblyScript

AssemblyScript is a TypeScript-to-WebAssembly compiler. Developed by Microsoft, TypeScript adds types to JavaScript. It has become quite popular, and even for people who are not familiar with it, AssemblyScript only allows for a limited subset of TypeScript features anyway, so it shouldn’t take long to get up to speed.

Because it’s so similar to JavaScript, AssemblyScript lets web developers easily incorporate WebAssembly into their websites without having to work with an entirely different language.

Trying it out

Let’s write our first AssemblyScript module (all of the following code is available in this GitHub repository). We need Node.js with a minimum version of 8 for WebAssembly support.

Change to an empty directory, create a package.json file, and install AssemblyScript. Note that we need to install it directly from its GitHub repository. It isn’t published on npm because the AssemblyScript developers don’t consider the compiler to be ready for general use yet.

mkdir assemblyscript-demo
cd assemblyscript-demo
npm init
npm install --save-dev github:AssemblyScript/assemblyscript

Generate scaffolding files using the included asinit command:

npx asinit .

Our package.json should now include these scripts:

{
  "scripts": {
    "asbuild:untouched": "asc assembly/index.ts -b build/untouched.wasm -t build/untouched.wat --sourceMap --validate --debug",
    "asbuild:optimized": "asc assembly/index.ts -b build/optimized.wasm -t build/optimized.wat --sourceMap --validate --optimize",
    "asbuild": "npm run asbuild:untouched && npm run asbuild:optimized"
  }
}

The top-level index.js looks like this:

const fs = require("fs");
const compiled = new WebAssembly.Module(fs.readFileSync(__dirname + "/build/optimized.wasm"));
const imports = {
  env: {
    abort(_msg, _file, line, column) {
       console.error("abort called at index.ts:" + line + ":" + column);
    }
  }
};
Object.defineProperty(module, "exports", {
  get: () => new WebAssembly.Instance(compiled, imports).exports
});

It allows us to easily [require](https://nodejs.org/api/modules.html#modules_require_id) our WebAssembly module just like a plain JavaScript module.

The assembly directory contains our AssemblyScript source code. The generated example is a simple addition function.

export function add(a: i32, b: i32): i32 {
  return a + b;
}

If you expect the function signature to look like add(a: number, b: number): number, as it would in TypeScript, the reason it uses i32 instead is that AssemblyScript uses WebAssembly’s specific integer and floating point types rather than TypeScript’s generic number type.

Let’s build the example.

npm run asbuild

The build directory should now include the following files:

optimized.wasm
optimized.wasm.map
optimized.wat
untouched.wasm
untouched.wasm.map
untouched.wat

We get plain and optimized versions of the build. For each build version, we get a .wasm binary, a .wasm.map source map, and a .wat textual representation of the binary. The textual representation is designed to be readable by humans, but for our purposes, we don’t need to read or understand it — part of the point of using AssemblyScript is that we don’t need to work with raw WebAssembly.

Fire up Node and use our compiled module just like any other module.

$ node
Welcome to Node.js v12.10.0.
Type ".help" for more information.
> const add = require('./index').add;
undefined
> add(3, 5)
8

And that’s all it took to call WebAssembly from Node!

Add a watch script

For development, I recommend using onchange to automatically rebuild the module whenever you change the source code because AssemblyScript doesn’t include a watch mode yet.

npm install --save-dev onchange

Add an asbuild:watch script to package.json. Include the -i flag to run an initial build as soon as you run the command.

{
  "scripts": {
    "asbuild:untouched": "asc assembly/index.ts -b build/untouched.wasm -t build/untouched.wat --sourceMap --validate --debug",
    "asbuild:optimized": "asc assembly/index.ts -b build/optimized.wasm -t build/optimized.wat --sourceMap --validate --optimize",
    "asbuild": "npm run asbuild:untouched && npm run asbuild:optimized",
    "asbuild:watch": "onchange -i 'assembly/**/*' -- npm run asbuild"
  }
}

Now you can run asbuild:watch instead of having to constantly rerun asbuild.

Performance

Let’s write a basic benchmark test to get an idea of what kind of performance boost we can get. WebAssembly’s specialty is handling CPU-intensive tasks like numerical calculations, so let’s go with a function for determining whether an integer is a prime number or not.

Our reference implementation looks like this. It’s a naive, brute-force solution because our goal is to perform a high number of calculations.

function isPrime(x) {
    if (x < 2) {
        return false;
    }

    for (let i = 2; i < x; i++) {
        if (x % i === 0) {
            return false;
        }
    }

    return true;
}

The equivalent AssemblyScript version just needs some type annotations:

function isPrime(x: u32): bool {
    if (x < 2) {
        return false;
    }

    for (let i: u32 = 2; i < x; i++) {
        if (x % i === 0) {
            return false;
        }
    }

    return true;
}

We’ll use Benchmark.js.

npm install --save-dev benchmark

Create benchmark.js:

const Benchmark = require('benchmark');

const assemblyScriptIsPrime = require('./index').isPrime;

function isPrime(x) {
    for (let i = 2; i < x; i++) {
        if (x % i === 0) {
            return false;
        }
    }

    return true;
}

const suite = new Benchmark.Suite;
const startNumber = 2;
const stopNumber = 10000;

suite.add('AssemblyScript isPrime', function () {
    for (let i = startNumber; i < stopNumber; i++) {
        assemblyScriptIsPrime(i);
    }
}).add('JavaScript isPrime', function () {
    for (let i = startNumber; i < stopNumber; i++) {
        isPrime(i);
    }
}).on('cycle', function (event) {
    console.log(String(event.target));
}).on('complete', function () {
    const fastest = this.filter('fastest');
    const slowest = this.filter('slowest');
    const difference = (fastest.map('hz') - slowest.map('hz')) / slowest.map('hz') * 100;
    console.log(`${fastest.map('name')} is ~${difference.toFixed(1)}% faster.`);
}).run();

On my machine, I got these results when I ran node benchmark:

AssemblyScript isPrime x 74.00 ops/sec ±0.43% (76 runs sampled)
JavaScript isPrime x 61.56 ops/sec ±0.30% (64 runs sampled)
AssemblyScript isPrime is ~20.2% faster.

Note that this test is a microbenchmark, and we should be careful about reading too much into it.

For some more involved AssemblyScript benchmarks, I recommend checking out this WasmBoy benchmark and this wave equation benchmark.

Loading the module

Next, let’s use our module in a website. Create index.html:

<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8" />
        <title>AssemblyScript isPrime demo</title>
    </head>
    <body>
        <form id="prime-checker">
            <label for="number">Enter a number to check if it is prime:</label>
            <input name="number" type="number" />
            <button type="submit">Submit</button>
        </form>

        <p id="result"></p>

        <script src="demo.js"></script>
    </body>
</html>

Create demo.js. There are multiple ways to load WebAssembly modules, but the most efficient is to compile and instantiate them in a streaming manner with the [WebAssembly.instantiateStreaming](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/WebAssembly/instantiateStreaming) function. Note that we need to provide an abort function, which is called if an assertion fails.

(async () => {
    const importObject = {
        env: {
            abort(_msg, _file, line, column) {
                console.error("abort called at index.ts:" + line + ":" + column);
            }
        }
    };
    const module = await WebAssembly.instantiateStreaming(
        fetch("build/optimized.wasm"),
        importObject
    );
    const isPrime = module.instance.exports.isPrime;

    const result = document.querySelector("#result");
    document.querySelector("#prime-checker").addEventListener("submit", event => {
        event.preventDefault();
        result.innerText = "";
        const number = event.target.elements.number.value;
        result.innerText = `${number} is ${isPrime(number) ? '' : 'not '}prime.`;
    });
})();

Now install static-server. We need a server because in order to use WebAssembly.instantiateStreaming, the module needs to be served with a MIME type of application/wasm.

npm install --save-dev static-server

Add a script to package.json.

{
  "scripts": {
    "serve-demo": "static-server"
  }
}

Run npm run serve-demo and open the localhost URL in a browser. Submit a number in the form, and you should get a message indicating whether the number is prime or not. Now we’ve gone all the way from writing AssemblyScript to actually using it in a website.

Conclusion

WebAssembly, and by extension AssemblyScript, is not going to magically make every website faster, but that was never the point. WebAssembly is exciting because it can make the web viable for a much larger set of applications.

Similarly, AssemblyScript makes WebAssembly accessible for more developers, making it easy for us to stick with JavaScript by default but bring in WebAssembly when we have work that requires lots of number crunching.

#WebAssembly #web-development #javascript #AssemblyScript

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Getting Started with AssemblyScript
Carmen  Grimes

Carmen Grimes

1595494844

How to start an electric scooter facility/fleet in a university campus/IT park

Are you leading an organization that has a large campus, e.g., a large university? You are probably thinking of introducing an electric scooter/bicycle fleet on the campus, and why wouldn’t you?

Introducing micro-mobility in your campus with the help of such a fleet would help the people on the campus significantly. People would save money since they don’t need to use a car for a short distance. Your campus will see a drastic reduction in congestion, moreover, its carbon footprint will reduce.

Micro-mobility is relatively new though and you would need help. You would need to select an appropriate fleet of vehicles. The people on your campus would need to find electric scooters or electric bikes for commuting, and you need to provide a solution for this.

To be more specific, you need a short-term electric bike rental app. With such an app, you will be able to easily offer micro-mobility to the people on the campus. We at Devathon have built Autorent exactly for this.

What does Autorent do and how can it help you? How does it enable you to introduce micro-mobility on your campus? We explain these in this article, however, we will touch upon a few basics first.

Micro-mobility: What it is

micro-mobility

You are probably thinking about micro-mobility relatively recently, aren’t you? A few relevant insights about it could help you to better appreciate its importance.

Micro-mobility is a new trend in transportation, and it uses vehicles that are considerably smaller than cars. Electric scooters (e-scooters) and electric bikes (e-bikes) are the most popular forms of micro-mobility, however, there are also e-unicycles and e-skateboards.

You might have already seen e-scooters, which are kick scooters that come with a motor. Thanks to its motor, an e-scooter can achieve a speed of up to 20 km/h. On the other hand, e-bikes are popular in China and Japan, and they come with a motor, and you can reach a speed of 40 km/h.

You obviously can’t use these vehicles for very long commutes, however, what if you need to travel a short distance? Even if you have a reasonable public transport facility in the city, it might not cover the route you need to take. Take the example of a large university campus. Such a campus is often at a considerable distance from the central business district of the city where it’s located. While public transport facilities may serve the central business district, they wouldn’t serve this large campus. Currently, many people drive their cars even for short distances.

As you know, that brings its own set of challenges. Vehicular traffic adds significantly to pollution, moreover, finding a parking spot can be hard in crowded urban districts.

Well, you can reduce your carbon footprint if you use an electric car. However, electric cars are still new, and many countries are still building the necessary infrastructure for them. Your large campus might not have the necessary infrastructure for them either. Presently, electric cars don’t represent a viable option in most geographies.

As a result, you need to buy and maintain a car even if your commute is short. In addition to dealing with parking problems, you need to spend significantly on your car.

All of these factors have combined to make people sit up and think seriously about cars. Many people are now seriously considering whether a car is really the best option even if they have to commute only a short distance.

This is where micro-mobility enters the picture. When you commute a short distance regularly, e-scooters or e-bikes are viable options. You limit your carbon footprints and you cut costs!

Businesses have seen this shift in thinking, and e-scooter companies like Lime and Bird have entered this field in a big way. They let you rent e-scooters by the minute. On the other hand, start-ups like Jump and Lyft have entered the e-bike market.

Think of your campus now! The people there might need to travel short distances within the campus, and e-scooters can really help them.

How micro-mobility can benefit you

benefits-micromobility

What advantages can you get from micro-mobility? Let’s take a deeper look into this question.

Micro-mobility can offer several advantages to the people on your campus, e.g.:

  • Affordability: Shared e-scooters are cheaper than other mass transportation options. Remember that the people on your campus will use them on a shared basis, and they will pay for their short commutes only. Well, depending on your operating model, you might even let them use shared e-scooters or e-bikes for free!
  • Convenience: Users don’t need to worry about finding parking spots for shared e-scooters since these are small. They can easily travel from point A to point B on your campus with the help of these e-scooters.
  • Environmentally sustainable: Shared e-scooters reduce the carbon footprint, moreover, they decongest the roads. Statistics from the pilot programs in cities like Portland and Denver showimpressive gains around this key aspect.
  • Safety: This one’s obvious, isn’t it? When people on your campus use small e-scooters or e-bikes instead of cars, the problem of overspeeding will disappear. you will see fewer accidents.

#android app #autorent #ios app #mobile app development #app like bird #app like bounce #app like lime #autorent #bird scooter business model #bird scooter rental #bird scooter rental cost #bird scooter rental price #clone app like bird #clone app like bounce #clone app like lime #electric rental scooters #electric scooter company #electric scooter rental business #how do you start a moped #how to start a moped #how to start a scooter rental business #how to start an electric company #how to start electric scooterrental business #lime scooter business model #scooter franchise #scooter rental business #scooter rental business for sale #scooter rental business insurance #scooters franchise cost #white label app like bird #white label app like bounce #white label app like lime

How to Get Current URL in Laravel

In this small post we will see how to get current url in laravel, if you want to get current page url in laravel then we can use many method such type current(), full(), request(), url().

Here i will give you all example to get current page url in laravel, in this example i have used helper and function as well as so let’s start example of how to get current url id in laravel.

Read More : How to Get Current URL in Laravel

https://websolutionstuff.com/post/how-to-get-current-url-in-laravel


Read More : Laravel Signature Pad Example

https://websolutionstuff.com/post/laravel-signature-pad-example

#how to get current url in laravel #laravel get current url #get current page url in laravel #find current url in laravel #get full url in laravel #how to get current url id in laravel

Ian  Robinson

Ian Robinson

1623993300

4 Key Tips to Get Started With Data Democratization

Data democratization means the cycle where one can utilize the data whenever to make decisions.

Business data is more bountiful than ever. Regardless of whether this data is gathered directly or bought from a third-party or syndicated source, it must be appropriately managed to bring organizations the most worth.

To achieve this goal, organizations are putting resources into data infrastructure and platforms, for example, data lakes and data warehouses. This investment is crucial to harnessing insights, yet it’s only essential for the solution.

Organizations are quickly embracing data-driven decision making processes. With insight-driven organizations growing multiple times quicker than their competitors, they don’t have a choice.

The gauntlet has adequately been tossed down. Either give admittance to significant data for your business, or join the developing memorial park of dinosaur organizations, incapable or reluctant to adapt to the cutting-edge digital economy

Self-service BI and analytics solutions can address this challenge by empowering business owners to access data straightforwardly and gain the insights they need. Nonetheless, just offering Self-service BI doesn’t ensure that an organization will become insights-rich and that key partners will be able to follow up on insights without contribution from technical team members.

The progress to genuinely insights-driven decisions requires a purposeful leadership effort, investment in the correct devices, and employee empowerment with the goal that leaders across capacities can counsel data independently prior to acting.

As such, organizations must take a stab at data democratization: opening up admittance to data and analytics among non-technical people without technical guards. In data democratization, the user experience must line up with the practices and needs of business owners to guarantee maximum adoption.

Data democratization means the process where one can utilize the data whenever to make decisions. In the company, everybody profits by having snappy admittance to data and the capacity to make decisions instantly.

Deploying data democratization requires data program to be self-aware; that is, with more prominent broad admittance to data, protocols should be set up to guarantee that users presented to certain data comprehend what it is they’re seeing — that nothing is misconstrued when deciphered and that overall data security itself is kept up, as more noteworthy availability to data may likewise effectively build risk to data integrity. These protections, while vital, are far exceeded by the perception of and data contribution from all edges of a company. With support empowered and encouraged across a company’s ecosystem,further knowledge becomes conceivable, driving advancement and better performance.

#big data #data management #latest news #4 key tips to get started with data democratization #data democratization #key tips to get started with data democratization

Carmen  Grimes

Carmen Grimes

1595491178

Best Electric Bikes and Scooters for Rental Business or Campus Facility

The electric scooter revolution has caught on super-fast taking many cities across the globe by storm. eScooters, a renovated version of old-school scooters now turned into electric vehicles are an environmentally friendly solution to current on-demand commute problems. They work on engines, like cars, enabling short traveling distances without hassle. The result is that these groundbreaking electric machines can now provide faster transport for less — cheaper than Uber and faster than Metro.

Since they are durable, fast, easy to operate and maintain, and are more convenient to park compared to four-wheelers, the eScooters trend has and continues to spike interest as a promising growth area. Several companies and universities are increasingly setting up shop to provide eScooter services realizing a would-be profitable business model and a ready customer base that is university students or residents in need of faster and cheap travel going about their business in school, town, and other surrounding areas.

Electric Scooters Trends and Statistics

In many countries including the U.S., Canada, Mexico, U.K., Germany, France, China, Japan, India, Brazil and Mexico and more, a growing number of eScooter users both locals and tourists can now be seen effortlessly passing lines of drivers stuck in the endless and unmoving traffic.

A recent report by McKinsey revealed that the E-Scooter industry will be worth― $200 billion to $300 billion in the United States, $100 billion to $150 billion in Europe, and $30 billion to $50 billion in China in 2030. The e-Scooter revenue model will also spike and is projected to rise by more than 20% amounting to approximately $5 billion.

And, with a necessity to move people away from high carbon prints, traffic and congestion issues brought about by car-centric transport systems in cities, more and more city planners are developing more bike/scooter lanes and adopting zero-emission plans. This is the force behind the booming electric scooter market and the numbers will only go higher and higher.

Companies that have taken advantage of the growing eScooter trend develop an appthat allows them to provide efficient eScooter services. Such an app enables them to be able to locate bike pick-up and drop points through fully integrated google maps.

List of Best Electric Bikes for Rental Business or Campus Facility 2020:

It’s clear that e scooters will increasingly become more common and the e-scooter business model will continue to grab the attention of manufacturers, investors, entrepreneurs. All this should go ahead with a quest to know what are some of the best electric bikes in the market especially for anyone who would want to get started in the electric bikes/scooters rental business.

We have done a comprehensive list of the best electric bikes! Each bike has been reviewed in depth and includes a full list of specs and a photo.

Billy eBike

mobile-best-electric-bikes-scooters https://www.kickstarter.com/projects/enkicycles/billy-were-redefining-joyrides

To start us off is the Billy eBike, a powerful go-anywhere urban electric bike that’s specially designed to offer an exciting ride like no other whether you want to ride to the grocery store, cafe, work or school. The Billy eBike comes in 4 color options – Billy Blue, Polished aluminium, Artic white, and Stealth black.

Price: $2490

Available countries

Available in the USA, Europe, Asia, South Africa and Australia.This item ships from the USA. Buyers are therefore responsible for any taxes and/or customs duties incurred once it arrives in your country.

Features

  • Control – Ride with confidence with our ultra-wide BMX bars and a hyper-responsive twist throttle.
  • Stealth- Ride like a ninja with our Gates carbon drive that’s as smooth as butter and maintenance-free.
  • Drive – Ride further with our high torque fat bike motor, giving a better climbing performance.
  • Accelerate – Ride quicker with our 20-inch lightweight cutout rims for improved acceleration.
  • Customize – Ride your own way with 5 levels of power control. Each level determines power and speed.
  • Flickable – Ride harder with our BMX /MotoX inspired geometry and lightweight aluminum package

Specifications

  • Maximum speed: 20 mph (32 km/h)
  • Range per charge: 41 miles (66 km)
  • Maximum Power: 500W
  • Motor type: Fat Bike Motor: Bafang RM G060.500.DC
  • Load capacity: 300lbs (136kg)
  • Battery type: 13.6Ah Samsung lithium-ion,
  • Battery capacity: On/off-bike charging available
  • Weight: w/o batt. 48.5lbs (22kg), w/ batt. 54lbs (24.5kg)
  • Front Suspension: Fully adjustable air shock, preload/compression damping /lockout
  • Rear Suspension: spring, preload adjustment
  • Built-in GPS

Why Should You Buy This?

  • Riding fun and excitement
  • Better climbing ability and faster acceleration.
  • Ride with confidence
  • Billy folds for convenient storage and transportation.
  • Shorty levers connect to disc brakes ensuring you stop on a dime
  • belt drives are maintenance-free and clean (no oil or lubrication needed)

**Who Should Ride Billy? **

Both new and experienced riders

**Where to Buy? **Local distributors or ships from the USA.

Genze 200 series e-Bike

genze-best-electric-bikes-scooters https://www.genze.com/fleet/

Featuring a sleek and lightweight aluminum frame design, the 200-Series ebike takes your riding experience to greater heights. Available in both black and white this ebike comes with a connected app, which allows you to plan activities, map distances and routes while also allowing connections with fellow riders.

Price: $2099.00

Available countries

The Genze 200 series e-Bike is available at GenZe retail locations across the U.S or online via GenZe.com website. Customers from outside the US can ship the product while incurring the relevant charges.

Features

  • 2 Frame Options
  • 2 Sizes
  • Integrated/Removable Battery
  • Throttle and Pedal Assist Ride Modes
  • Integrated LCD Display
  • Connected App
  • 24 month warranty
  • GPS navigation
  • Bluetooth connectivity

Specifications

  • Maximum speed: 20 mph with throttle
  • Range per charge: 15-18 miles w/ throttle and 30-50 miles w/ pedal assist
  • Charging time: 3.5 hours
  • Motor type: Brushless Rear Hub Motor
  • Gears: Microshift Thumb Shifter
  • Battery type: Removable Samsung 36V, 9.6AH Li-Ion battery pack
  • Battery capacity: 36V and 350 Wh
  • Weight: 46 pounds
  • Derailleur: 8-speed Shimano
  • Brakes: Dual classic
  • Wheels: 26 x 20 inches
  • Frame: 16, and 18 inches
  • Operating Mode: Analog mode 5 levels of Pedal Assist Thrott­le Mode

Norco from eBikestore

norco-best-electric-bikes-scooters https://ebikestore.com/shop/norco-vlt-s2/

The Norco VLT S2 is a front suspension e-Bike with solid components alongside the reliable Bosch Performance Line Power systems that offer precise pedal assistance during any riding situation.

Price: $2,699.00

Available countries

This item is available via the various Norco bikes international distributors.

Features

  • VLT aluminum frame- for stiffness and wheel security.
  • Bosch e-bike system – for their reliability and performance.
  • E-bike components – for added durability.
  • Hydraulic disc brakes – offer riders more stopping power for safety and control at higher speeds.
  • Practical design features – to add convenience and versatility.

Specifications

  • Maximum speed: KMC X9 9spd
  • Motor type: Bosch Active Line
  • Gears: Shimano Altus RD-M2000, SGS, 9 Speed
  • Battery type: Power Pack 400
  • Battery capacity: 396Wh
  • Suspension: SR Suntour suspension fork
  • Frame: Norco VLT, Aluminum, 12x142mm TA Dropouts

Bodo EV

bodo-best-electric-bikes-scootershttp://www.bodoevs.com/bodoev/products_show.asp?product_id=13

Manufactured by Bodo Vehicle Group Limited, the Bodo EV is specially designed for strong power and extraordinary long service to facilitate super amazing rides. The Bodo Vehicle Company is a striking top in electric vehicles brand field in China and across the globe. Their Bodo EV will no doubt provide your riders with high-level riding satisfaction owing to its high-quality design, strength, breaking stability and speed.

Price: $799

Available countries

This item ships from China with buyers bearing the shipping costs and other variables prior to delivery.

Features

  • Reliable
  • Environment friendly
  • Comfortable riding
  • Fashionable
  • Economical
  • Durable – long service life
  • Braking stability
  • LED lighting technology

Specifications

  • Maximum speed: 45km/h
  • Range per charge: 50km per person
  • Charging time: 8 hours
  • Maximum Power: 3000W
  • Motor type: Brushless DC Motor
  • Load capacity: 100kg
  • Battery type: Lead-acid battery
  • Battery capacity: 60V 20AH
  • Weight: w/o battery 47kg

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Getting Started with AssemblyScript

WebAssembly (or Wasm) is a relatively recent addition to web browsers, but it has the potential to drastically expand what the web is capable of as a platform for serving applications.

While there can be a steep learning curve for web developers to get started with WebAssembly, AssemblyScript provides a way to get around that. Let’s first take a look at why WebAssembly is such a promising technology, and then we’ll see how AssemblyScript can help to unlock its potential.

WebAssembly

WebAssembly is a low-level language for browsers, giving developers a compilation target for the web besides JavaScript. It makes it possible for website code to run at near-native speed in a safe, sandboxed environment.

It was developed with input from representatives of all the major browsers (Chrome, Firefox, Safari, and Edge), who reached a design consensus in early 2017. All of these browsers now support WebAssembly, which is usable in about 87 percent of all browsers.

WebAssembly is delivered in a binary format, which means that it has both size and load time advantages over JavaScript. Yet it also has a textual representation that is human-readable.

When WebAssembly was first announced, some developers thought it had the potential to eventually supplant JavaScript as the primary language of the web. But it’s better to think of WebAssembly as a new tool that integrates well with the existing web platform, which is one of its high-level goals.

Rather than replacing JavaScript for existing use cases, WebAssembly is intriguing more because it enables new use cases. WebAssembly doesn’t have direct access to the DOM yet, and most existing websites will want to stick with JavaScript, which is already quite fast after going through years of optimization. Here’s a sample of WebAssembly’s own list of possible use cases:

  • Games
  • Scientific visualization and simulation
  • CAD applications
  • Image/video editing

The common attribute among these applications is that we would typically think of them as desktop applications. By providing near-native performance for CPU-intensive tasks, WebAssembly makes it feasible to move more of these applications to the web.

Existing websites can also benefit from WebAssembly. Figma provides a real-world example, having used WebAssembly to significantly improve their load time. If a website uses code that does a lot of computation, it can make sense to replace only that code with WebAssembly to improve performance.

So maybe now you’re interested in getting started with WebAssembly. You could learn the language itself and write it directly, but it was really intended to be a compilation target for other languages. It was designed to have good support for C and C++, Go added experimental support for it in version 1.11, and Rust is also investing heavily in it.

But maybe you don’t want to learn or use one of these languages in order to use WebAssembly. This is where AssemblyScript comes into play.

AssemblyScript

AssemblyScript is a TypeScript-to-WebAssembly compiler. Developed by Microsoft, TypeScript adds types to JavaScript. It has become quite popular, and even for people who are not familiar with it, AssemblyScript only allows for a limited subset of TypeScript features anyway, so it shouldn’t take long to get up to speed.

Because it’s so similar to JavaScript, AssemblyScript lets web developers easily incorporate WebAssembly into their websites without having to work with an entirely different language.

Trying it out

Let’s write our first AssemblyScript module (all of the following code is available in this GitHub repository). We need Node.js with a minimum version of 8 for WebAssembly support.

Change to an empty directory, create a package.json file, and install AssemblyScript. Note that we need to install it directly from its GitHub repository. It isn’t published on npm because the AssemblyScript developers don’t consider the compiler to be ready for general use yet.

mkdir assemblyscript-demo
cd assemblyscript-demo
npm init
npm install --save-dev github:AssemblyScript/assemblyscript

Generate scaffolding files using the included asinit command:

npx asinit .

Our package.json should now include these scripts:

{
  "scripts": {
    "asbuild:untouched": "asc assembly/index.ts -b build/untouched.wasm -t build/untouched.wat --sourceMap --validate --debug",
    "asbuild:optimized": "asc assembly/index.ts -b build/optimized.wasm -t build/optimized.wat --sourceMap --validate --optimize",
    "asbuild": "npm run asbuild:untouched && npm run asbuild:optimized"
  }
}

The top-level index.js looks like this:

const fs = require("fs");
const compiled = new WebAssembly.Module(fs.readFileSync(__dirname + "/build/optimized.wasm"));
const imports = {
  env: {
    abort(_msg, _file, line, column) {
       console.error("abort called at index.ts:" + line + ":" + column);
    }
  }
};
Object.defineProperty(module, "exports", {
  get: () => new WebAssembly.Instance(compiled, imports).exports
});

It allows us to easily [require](https://nodejs.org/api/modules.html#modules_require_id) our WebAssembly module just like a plain JavaScript module.

The assembly directory contains our AssemblyScript source code. The generated example is a simple addition function.

export function add(a: i32, b: i32): i32 {
  return a + b;
}

If you expect the function signature to look like add(a: number, b: number): number, as it would in TypeScript, the reason it uses i32 instead is that AssemblyScript uses WebAssembly’s specific integer and floating point types rather than TypeScript’s generic number type.

Let’s build the example.

npm run asbuild

The build directory should now include the following files:

optimized.wasm
optimized.wasm.map
optimized.wat
untouched.wasm
untouched.wasm.map
untouched.wat

We get plain and optimized versions of the build. For each build version, we get a .wasm binary, a .wasm.map source map, and a .wat textual representation of the binary. The textual representation is designed to be readable by humans, but for our purposes, we don’t need to read or understand it — part of the point of using AssemblyScript is that we don’t need to work with raw WebAssembly.

Fire up Node and use our compiled module just like any other module.

$ node
Welcome to Node.js v12.10.0.
Type ".help" for more information.
> const add = require('./index').add;
undefined
> add(3, 5)
8

And that’s all it took to call WebAssembly from Node!

Add a watch script

For development, I recommend using onchange to automatically rebuild the module whenever you change the source code because AssemblyScript doesn’t include a watch mode yet.

npm install --save-dev onchange

Add an asbuild:watch script to package.json. Include the -i flag to run an initial build as soon as you run the command.

{
  "scripts": {
    "asbuild:untouched": "asc assembly/index.ts -b build/untouched.wasm -t build/untouched.wat --sourceMap --validate --debug",
    "asbuild:optimized": "asc assembly/index.ts -b build/optimized.wasm -t build/optimized.wat --sourceMap --validate --optimize",
    "asbuild": "npm run asbuild:untouched && npm run asbuild:optimized",
    "asbuild:watch": "onchange -i 'assembly/**/*' -- npm run asbuild"
  }
}

Now you can run asbuild:watch instead of having to constantly rerun asbuild.

Performance

Let’s write a basic benchmark test to get an idea of what kind of performance boost we can get. WebAssembly’s specialty is handling CPU-intensive tasks like numerical calculations, so let’s go with a function for determining whether an integer is a prime number or not.

Our reference implementation looks like this. It’s a naive, brute-force solution because our goal is to perform a high number of calculations.

function isPrime(x) {
    if (x < 2) {
        return false;
    }

    for (let i = 2; i < x; i++) {
        if (x % i === 0) {
            return false;
        }
    }

    return true;
}

The equivalent AssemblyScript version just needs some type annotations:

function isPrime(x: u32): bool {
    if (x < 2) {
        return false;
    }

    for (let i: u32 = 2; i < x; i++) {
        if (x % i === 0) {
            return false;
        }
    }

    return true;
}

We’ll use Benchmark.js.

npm install --save-dev benchmark

Create benchmark.js:

const Benchmark = require('benchmark');

const assemblyScriptIsPrime = require('./index').isPrime;

function isPrime(x) {
    for (let i = 2; i < x; i++) {
        if (x % i === 0) {
            return false;
        }
    }

    return true;
}

const suite = new Benchmark.Suite;
const startNumber = 2;
const stopNumber = 10000;

suite.add('AssemblyScript isPrime', function () {
    for (let i = startNumber; i < stopNumber; i++) {
        assemblyScriptIsPrime(i);
    }
}).add('JavaScript isPrime', function () {
    for (let i = startNumber; i < stopNumber; i++) {
        isPrime(i);
    }
}).on('cycle', function (event) {
    console.log(String(event.target));
}).on('complete', function () {
    const fastest = this.filter('fastest');
    const slowest = this.filter('slowest');
    const difference = (fastest.map('hz') - slowest.map('hz')) / slowest.map('hz') * 100;
    console.log(`${fastest.map('name')} is ~${difference.toFixed(1)}% faster.`);
}).run();

On my machine, I got these results when I ran node benchmark:

AssemblyScript isPrime x 74.00 ops/sec ±0.43% (76 runs sampled)
JavaScript isPrime x 61.56 ops/sec ±0.30% (64 runs sampled)
AssemblyScript isPrime is ~20.2% faster.

Note that this test is a microbenchmark, and we should be careful about reading too much into it.

For some more involved AssemblyScript benchmarks, I recommend checking out this WasmBoy benchmark and this wave equation benchmark.

Loading the module

Next, let’s use our module in a website. Create index.html:

<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8" />
        <title>AssemblyScript isPrime demo</title>
    </head>
    <body>
        <form id="prime-checker">
            <label for="number">Enter a number to check if it is prime:</label>
            <input name="number" type="number" />
            <button type="submit">Submit</button>
        </form>

        <p id="result"></p>

        <script src="demo.js"></script>
    </body>
</html>

Create demo.js. There are multiple ways to load WebAssembly modules, but the most efficient is to compile and instantiate them in a streaming manner with the [WebAssembly.instantiateStreaming](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/WebAssembly/instantiateStreaming) function. Note that we need to provide an abort function, which is called if an assertion fails.

(async () => {
    const importObject = {
        env: {
            abort(_msg, _file, line, column) {
                console.error("abort called at index.ts:" + line + ":" + column);
            }
        }
    };
    const module = await WebAssembly.instantiateStreaming(
        fetch("build/optimized.wasm"),
        importObject
    );
    const isPrime = module.instance.exports.isPrime;

    const result = document.querySelector("#result");
    document.querySelector("#prime-checker").addEventListener("submit", event => {
        event.preventDefault();
        result.innerText = "";
        const number = event.target.elements.number.value;
        result.innerText = `${number} is ${isPrime(number) ? '' : 'not '}prime.`;
    });
})();

Now install static-server. We need a server because in order to use WebAssembly.instantiateStreaming, the module needs to be served with a MIME type of application/wasm.

npm install --save-dev static-server

Add a script to package.json.

{
  "scripts": {
    "serve-demo": "static-server"
  }
}

Run npm run serve-demo and open the localhost URL in a browser. Submit a number in the form, and you should get a message indicating whether the number is prime or not. Now we’ve gone all the way from writing AssemblyScript to actually using it in a website.

Conclusion

WebAssembly, and by extension AssemblyScript, is not going to magically make every website faster, but that was never the point. WebAssembly is exciting because it can make the web viable for a much larger set of applications.

Similarly, AssemblyScript makes WebAssembly accessible for more developers, making it easy for us to stick with JavaScript by default but bring in WebAssembly when we have work that requires lots of number crunching.

#WebAssembly #web-development #javascript #AssemblyScript