How to Build Reusable Web Components Using Stencil.js

Stencil is a compiler for generating web components developed by the Ionic team. Web components in Stencil can be used as standalone components, as a part of a Stencil web application, and as part of Ionic progressive web applications.

According to the Ionic team, Stencil should not be called a framework, but it looks like a framework to me :).

A web component (in case you missed it) is nothing more than a custom HTML tag () packed with additional logic written in JavaScript.

Components in Stencil are written in TypeScript and then compiled into various versions of JavaScript. Various bundles produced by a compiler are meant to be used in different scenarios. Everything is covered, from older browsers with polyfills to the newer ones with all of the shiny JavaScript features included. It is the same as Differential Loading in Angular.

Stencil looks like a mixture of React and Angular. Developers from both teams will find many familiar concepts and keywords, and because of that, learning Stencil should be easy-peasy.

In this introductory example, we can spot a component decorator with a render method using JSX.

import { Component, Prop, h } from '@stencil/core';

@Component({
  tag: 'my-first-component',
})
export class MyComponent {

  // Indicate that name should be a public property on the component
  @Prop() name: string;

  render() {
    return (
      <p>
        My name is {this.name}
      </p>
    );
  }
}

And the Prop is similar to the Input tag in Angular.

Stencil:

  • Can be combined with all major front-end frameworks, as well as with other JavaScript libraries or with no library at all

  • It does not require run-time (like Angular, React, Vue…). A produced JavaScript bundle is all that is needed in order for it to be used

  • It is fully aligned with the implementation of Custom Elements v1

  • Production bundle size start from ~100 kb and with polyfills ~133 kb (we can gzip it)

Browser support

In general, web components (and Stencil) are supported across all major browsers. They’re only not supported by Edge versions from 12 to 18 (that is before the WebKit implementation). Anyway, it is only 2% of all used browsers in the world.

The main user of Stencil is Ionic framework and all it’s UI components are built using Stencil. Go through a few of them, from the previous link, see how they did it. Reading quality code can be a great way to learn

Getting started

Stencil provides great tooling out of the box. It comes with an integrated development server, a generator for components, a compiler for all sorts of bundles, a doc generator, and a testing suite.

Prerequisites

We have to install the latest LTS version of Node and NPM in order to work with it. You should validate what you have first with:

node -v
npm -v

Ensure that we have Node.js ≥ 12 and NPM version ≥ 6.

We have to install Stencil as a global package:

npm install -g stencil

Extensions of components are TSX because it uses JSX as a templating language.

Now, if we want to generate our project, we will have to use an interactive wizard provided by Stencil trough NPM init:

npm init stencil

To demonstrate its usage, let’s build a simple cryptocurrency widget.

We want to build a reusable component so we will choose the third option, component.

This is image title

And after a few seconds you should see:

This is image title

Creating a component

First, we will remove the generated component my-component from the code. Feel free to delete it.

After, using npm run generate, we will generate our first component:

This is image title

It’s important that our component has a name with a dash. In our case, it is crypto-view. This will be the name of our custom HTML tag .

Manually, we have to replace references from my-component to crypto-view in src/index.html in order to get the development server working again:

This is image title

This is what our generated component looks like:

import { Component, Host, h } from '@stencil/core';

@Component({
  tag: 'crypto-view',
  styleUrl: 'crypto-view.css',
  shadow: true
})
export class CryptoView {

  render() {
    return (
      <Host>
        <slot></slot>
      </Host>
    );
  }

}

Immediately we can spot in our @Component decorator setting shadow: true. It’s very important that our main (entry ) component has this setting. Basically, it means that this element will be isolated from the rest of the DOM in our page with the shadow root:

This is image title

It further means that styles defined in crypto-view.css will not be applied to any element outside of the crypto-view component.

In the render method we have:

render() {
  return (
    <Host>
      <slot></slot>
    </Host>
  );
}

Host , as its name implies, refers to a host component. In our case, it is the element. Check out this quick example:

render() {
  return (
    <Host class={'hello'}>
      <slot></slot>
    </Host>
  );
}	
	

This will append class hello on crptyo-view component.

![This is image title](https://i0.wp.com/blog.logrocket.com/wp-content/uploads/2019/10/hello.png?w=643&ssl=1 "This is image title")	

*Class hydrated is added by Stenci *

In JSX we must have root (wrapping ) element. By default, it is Host in Stencil, but it can be DIV as well.

Among Host, we have slot. If you are coming from the Angular ecosystem, slot is ng-content. It will project any content passed between … tags. We can pass HTML, child components or text, and it will be projected on the place we define .

We can have multiple slots as well, take a look at this example:

<ui-component>
  <p slot='my-title'>Title</p>
  <p slot='my-description'>Description</p>
</ui-component>	
	

It can be rendered using the name attribute in slot:

render () {
  return (<div>
    <slot name='my-title' />
    <slot name='my-description' />
  </div>)
}	
	

CSS

Now let’s open the CSS file crypto-view.css:

:host {
  display: block;
}	

We will see that only :host is defined. Similar to the Host element in JSX code, :host refers to a host component , which has default display: block. Note that the majority of elements in HTML have display: block. Now when this is set, we can apply any CSS style to a host element through :host directive.

Props (attributes)

As we have to fetch crypto data from somewhere, we will use API from cryptocompare.com as it offers usage with free API Key.

The first prop that we will define will be apiKey. Prop names with camel case resolve to two words with a dash in between, because camel case is not supported in HTML, while in JSX it is supported.

![This is image title](https://i1.wp.com/blog.logrocket.com/wp-content/uploads/2019/10/prop.png?w=766&ssl=1 "This is image title")

And in our component:

import { Component, Host, h, Prop } from '@stencil/core';

@Component({
  tag: 'crypto-view',
  styleUrl: 'crypto-view.css',
  shadow: true
})
export class CryptoView {

  /**
   * Valid API key obtained from cryptocompare.com
   */
  @Prop() apiKey: string;

  componentDidLoad() {
    console.log(this.apiKey);
  }

  render() {
    return (
      <Host>
        <slot></slot>
      </Host>
    );
  }

}	

Lifecycle methods (Hooks)

Notice the componentDidLoad function, and console.log in it. If we run the application now, we will see our apiKey logged in the console.

Class method componentDidLoad is a lifecycle hook. Which means that it is triggered at a defined point in the life of the component. Developers from a React background will recognize the name.

Here are some commonly used Hooks ( lifecycle methods in Stencil ):

  • componentWillLoad() is triggered before rendering

  • componentDidLoad() is triggered after rendering ( inserting into the DOM)

  • componentWillUpdate() is triggered before updating

  • componentDidUpdate() is triggered after updating

  • componentDidUnload() is triggered after unmounting ( removing from the DOM)

We can find the full list and explanation on Stencil doc page for Lifecycle Methods.

In our case, as the apiKey is not asynchronously set we can use the
componentDidLoad Hook to get its value and call the API. Note that
componentDidLoad is called only once, while some lifecycle methods can be called multiple times.

We will create, in src/utils/utils.ts , the function getCryptoData which will fetch the latest price in USD and EUR for Bitcoin, Etherum, and Ripple.

import { CryptoInterface } from '../components/crypto-view/crypto.interface';

export function getCryptoData(apiKey: string): Promise<CryptoInterface> {
  return fetch(`https://min-api.cryptocompare.com/data/pricemulti?fsyms=BTC,ETH,XRP&tsyms=USD,EUR&api_key=${apiKey}`)
    .then(response => response.json());
}	
	

The response from the API is mapped to the interface in order to get typing support from the IDE ( in my case it is WebStrom).

export interface CryptoInterface {
  BTC: IPrices;
  ETH: IPrices;
  XRP: IPrices;
}

interface IPrices {
  USD: number;
  EUR: number;
}	

State

Response from the server is stored in the variable cryptoData which is decorated by @State.

import { Component, Host, h, Prop, State } from '@stencil/core';
import { getCryptoData } from '../../utils/utils';
import { CryptoInterface } from './crypto.interface';

@Component({
  tag: 'crypto-view',
  styleUrl: 'crypto-view.css',
  shadow: true
})
export class CryptoView {

  /**
   * Valid API key obtained from cryptocompare.com
   */
  @Prop() apiKey: string;

  @State() cryptoData: CryptoInterface;

  componentDidLoad() {
    getCryptoData(this.apiKey).then((data) => {
      this.cryptoData = data;
    });
  }

  render() {
    return (
      <Host>
        <slot></slot>
      </Host>
    );
  }

}	
	

Each change on a variable is annotated with the decorator State which will trigger the re-rendering of the component. It is the same as in React. In Angular, it is a different (and much longer) story.

In React, setting state is done with the internal method setState, which is equal to assigning value to the cryptoData variable in Stencil ( it is not a normal variable, it is state variable ).

In our case, we asynchronously get crypto data, and upon receiving it in the component, we assign it to the state variable cryptoData.

To present data, we will create another component called crypto-table:

This is image title

The crpyto table is a presentational component. Such a component only receives things through props and displays them into JSX. No internal state, no local computations and etc.

It looks like this:

import { Component, Host, h, Prop } from '@stencil/core';

import { CryptoInterface } from '../crypto-view/crypto.interface';

@Component({
  tag: 'crypto-table',
  styleUrl: 'crypto-table.css',
  shadow: false,
  scoped: true
})
export class CryptoTable {

  @Prop() cryptoData: CryptoInterface;
  @Prop() cryptoCurrencies: string[];

  render() {
    return (
      <Host>
        <table class={'crypto'}>
          <tr>
            <td></td>
            <td>USD</td>
            <td>EUR</td>
          </tr>
          {this.cryptoCurrencies.map((item) => {
            return this.cryptoData && item in this.cryptoData ? <tr>
              <td>{item}</td>
              <td>{this.cryptoData[item].USD}</td>
              <td>{this.cryptoData[item].EUR}</td>
            </tr> : null
          })}
        </table>
      </Host>
    );
  }

}	

Now, if you are familiar with React, Stencil uses JSX and the same principles for displaying data. If you come from Angular, forget about ngIf and ngFor directives, get used to JSX as soon as possible.

In this component, we will set shadow to false, as we don’t need to isolate this component further in the DOM. The new setting here is scoped: true, which adds additional CSS classes to each element in this component ( cs-crypto-table ):

This is image title

A combination of scoped and shadow attributes in the component decorator from Stencil are similar to ViewEncapsulation in Angular.

For creating dumb ( presentational ) components, we can use Functional Components approach. They are arrow functions that accept props as a parameter and return JSX.

In the CryptoView component we will inject CryptoTable and pass data through props bindings:

import { Component, Host, h, Prop, State } from '@stencil/core';
import { getCryptoData } from '../../utils/utils';
import { CryptoInterface } from './crypto.interface';

@Component({
  tag: 'crypto-view',
  styleUrl: 'crypto-view.css',
  shadow: true
})
export class CryptoView {

  /**
   * Valid API key obtained from cryptocompare.com
   */
  @Prop() apiKey: string;

  @State() cryptoData: CryptoInterface;

  cryptoCurrencies = ['BTC', 'ETH', 'XRP'];

  componentDidLoad() {
    getCryptoData(this.apiKey).then((data) => {
      this.cryptoData = data;
    });
  }

  render() {
    return (
      <Host>
        <b>Crypto data on date: {new Date().toLocaleDateString()}</b>
        <crypto-table cryptoData={this.cryptoData} cryptoCurrencies={this.cryptoCurrencies} />
        <slot></slot>
      </Host>
    );
  }

}	
	

Note that we didn’t have to import CryptoTable anywhere, that is all done by the Stencil compiler.

I grabbed CSS from W3school, and our crypto table looks something like this:

This is image title

Methods

If we imagine a scenario where the host application wants to refresh crypto data in our component. We must somehow expose method which will trigger re-fetching crypto data.

Stencil introduced the Method decorator for that purpose:

@Method()
async refreshCryptoData() {
  getCryptoData(this.apiKey).then((data) => {
    this.cryptoData = data;
  });
}	

The exposed class method must be marked as an async function. It is a requirement by Stencil.

Now, in index.html we can call it with:

<!DOCTYPE html>
<html dir="ltr" lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0, minimum-scale=1.0, maximum-scale=5.0">
  <title>Stencil Component Starter</title>

  <script type="module" src="/build/crypto-widget.esm.js"></script>
  <script nomodule src="/build/crypto-widget.js"></script>

</head>
<body>
    <crypto-view api-key="fd937be4428d64cf4dd1b51146aef28e46d224aea7ea5bdfbbb6d296a05ec1a9"></crypto-view>

    <script>
        document.addEventListener('DOMContentLoaded', (event) => {
            const cryptoView = document.querySelector('crypto-view');
            setTimeout(() => {
                cryptoView.refreshCryptoData();
            }, 2000);
        })
    </script>
</body>
</html>	
	

For the sake of the demo, we are waiting for two seconds and then calling method to refresh crypto data in our component.

Events

In Stencil, events are similar to Output in Angular where child component can emit something, and parent component can catch that. Events are used to push data from child components to parent components. That is similar to what we do every day in Angular and React.

There are two ways of catching events. One with an attribute on the component and the second one with Listen decorator.

First, let’s try to notify the parent component from the child component:

This is image title

Here is the code:

import { Component, Host, Event, h, EventEmitter } from '@stencil/core';

@Component({
  tag: 'crypto-refresher',
  styleUrl: 'crypto-refresher.css',
})
export class CryptoRefresher {

  @Event() refreshCryptoData: EventEmitter;

  refresh() {
    this.refreshCryptoData.emit(true);
  }

  render() {
    return (
      <Host>
        <button onClick={() => this.refresh()}>Refresh Crypto Data</button>
      </Host>
    );
  }

}	
	

Our refreshCryptoData is decorated with the Event decorator ( don’t forget to import it from @stencil/core ) and then emitted upon clicking on the button.

import { Component, Host, h, Prop, State, Method, Listen } from '@stencil/core';
import { getCryptoData } from '../../utils/utils';
import { CryptoInterface } from './crypto.interface';

@Component({
  tag: 'crypto-view',
  styleUrl: 'crypto-view.css',
  shadow: true
})
export class CryptoView {

  /**
   * Valid API key obtained from cryptocompare.com
   */
  @Prop() apikey: string;

  @State() cryptoData: CryptoInterface;

  cryptoCurrencies = ['BTC', 'ETH', 'XRP'];

  componentDidLoad() {
    this.fetchData();
  }

  fetchData() {
    getCryptoData(this.apikey).then((data) => {
      this.cryptoData = data;
    });
  }

  @Method()
  async refreshCryptoData() {
    this.fetchData();
  }

  @Listen('refreshCryptoData')
  listen(event) {
    console.log(event)
  }

  render() {
    return (
      <Host>
        <b>Crypto data on date: {new Date().toLocaleDateString()}</b>
        <crypto-table cryptoData={this.cryptoData} cryptoCurrencies={this.cryptoCurrencies} />
        <crypto-refresher onRefreshCryptoData={() => this.fetchData()} />
        <slot></slot>
      </Host>
    );
  }

}	

Notice that we use the shortened version of invoking component , it is the preferred way as we don’t project any data into it.

Let’s catch this event with an attribute on the component first.

In Stencil, we should name the attribute which catches our event with the prefix on. If our event is called, the attribute for catching it is onRefreshCryptoData. In our case, onRefreshCryptoData is an arrow function that will call the fetchData method.

In case we pass some data with the Event, we will have that data in arrow function parameters.

The second way to catch events is with the Listen decorator. It accepts the name of event as a parameter and calls the function bellow after catching it. The Listen decorator is handy when it comes to listening on system events like resize, scroll, etc. It is similar to HostListener in Angular.

Watch (reactivity)

Now, if want to listen on Props changes and call other methods or compute other things upon it, we have to use the Watch decorator.

If we, for example, want to compute the sum of prices in the crytpo table component and present that, we will have to wait for cryptoData to be fetched and passed, then compute the sum.

import { Component, Host, h, Prop, Watch, State } from '@stencil/core';

import { CryptoInterface } from '../crypto-view/crypto.interface';

@Component({
  tag: 'crypto-table',
  styleUrl: 'crypto-table.css',
  shadow: false,
  scoped: true
})
export class CryptoTable {

  @Prop() cryptoData: CryptoInterface;
  @Prop() cryptoCurrencies: string[];

  @State() sum: { USD: number, EUR: number };

  @Watch('cryptoData')
  watching(cryptoData: CryptoInterface) {
    this.sum = {
      USD: Math.round(cryptoData.BTC.USD + cryptoData.ETH.USD + cryptoData.XRP.USD),
      EUR: Math.round(cryptoData.BTC.EUR + cryptoData.ETH.EUR + cryptoData.XRP.EUR),
    }
  }

  render() {
    return (
      <Host>
        <table class={'crypto'}>
          <tr>
            <td></td>
            <td>USD</td>
            <td>EUR</td>
          </tr>
          {this.cryptoCurrencies.map((item) => {
            return this.cryptoData && item in this.cryptoData ? <tr>
              <td>{item}</td>
              <td>{this.cryptoData[item].USD}</td>
              <td>{this.cryptoData[item].EUR}</td>
            </tr> : null
          })}
          {this.sum ?
          <tr>
            <td></td>
            <td>{this.sum.USD}</td>
            <td>{this.sum.EUR}</td>
          </tr> : null }
        </table>
      </Host>
    );
  }

}				
				

In the example above, each time cryptoData is changed, the component will calculate the sum of all currencies.

Building and using

In order to build this project and produce shareable bundles, we have to run

npm run build				

The build will produce a dist folder and crypto-widget folder inside of it.

This is image title

It’s safe to grab this folder and copy it to a place where we want to include our component.

In HTML it is enough to include two files, first one is crypto-widget.js, it is an es5 bundle (with polyfills) meant to be used in older browsers (IE 11).

The second one is crypto-widget.esm.js, it comes with all new JavaScript features like code-splitting, async-await, etc.

<script type="module" src="/build/crypto-widget.esm.js"></script>
<script nomodule src="/build/crypto-widget.js"></script>				
				

Browsers are smart today, and they will load only what they need.

Conclusion

Stencil is a great library. It is well developed, well documented, battle-tested, backed by a big company, aligned with standards, and is very easy to learn.

Use cases for Stencil include:

  • Creating design systems for large projects and organizations ( shareable UI components )

  • Creating portable parts of applications that can be shared and used in many different places. ( viewers, widgets, integrations, etc. )

You can find the GitHub repo for this project here.

This article has been originally written by Vlado Tesanovic at blog.logrocket

#Stencil #javascript

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Buddha Community

How to Build Reusable Web Components Using Stencil.js

NBB: Ad-hoc CLJS Scripting on Node.js

Nbb

Not babashka. Node.js babashka!?

Ad-hoc CLJS scripting on Node.js.

Status

Experimental. Please report issues here.

Goals and features

Nbb's main goal is to make it easy to get started with ad hoc CLJS scripting on Node.js.

Additional goals and features are:

  • Fast startup without relying on a custom version of Node.js.
  • Small artifact (current size is around 1.2MB).
  • First class macros.
  • Support building small TUI apps using Reagent.
  • Complement babashka with libraries from the Node.js ecosystem.

Requirements

Nbb requires Node.js v12 or newer.

How does this tool work?

CLJS code is evaluated through SCI, the same interpreter that powers babashka. Because SCI works with advanced compilation, the bundle size, especially when combined with other dependencies, is smaller than what you get with self-hosted CLJS. That makes startup faster. The trade-off is that execution is less performant and that only a subset of CLJS is available (e.g. no deftype, yet).

Usage

Install nbb from NPM:

$ npm install nbb -g

Omit -g for a local install.

Try out an expression:

$ nbb -e '(+ 1 2 3)'
6

And then install some other NPM libraries to use in the script. E.g.:

$ npm install csv-parse shelljs zx

Create a script which uses the NPM libraries:

(ns script
  (:require ["csv-parse/lib/sync$default" :as csv-parse]
            ["fs" :as fs]
            ["path" :as path]
            ["shelljs$default" :as sh]
            ["term-size$default" :as term-size]
            ["zx$default" :as zx]
            ["zx$fs" :as zxfs]
            [nbb.core :refer [*file*]]))

(prn (path/resolve "."))

(prn (term-size))

(println (count (str (fs/readFileSync *file*))))

(prn (sh/ls "."))

(prn (csv-parse "foo,bar"))

(prn (zxfs/existsSync *file*))

(zx/$ #js ["ls"])

Call the script:

$ nbb script.cljs
"/private/tmp/test-script"
#js {:columns 216, :rows 47}
510
#js ["node_modules" "package-lock.json" "package.json" "script.cljs"]
#js [#js ["foo" "bar"]]
true
$ ls
node_modules
package-lock.json
package.json
script.cljs

Macros

Nbb has first class support for macros: you can define them right inside your .cljs file, like you are used to from JVM Clojure. Consider the plet macro to make working with promises more palatable:

(defmacro plet
  [bindings & body]
  (let [binding-pairs (reverse (partition 2 bindings))
        body (cons 'do body)]
    (reduce (fn [body [sym expr]]
              (let [expr (list '.resolve 'js/Promise expr)]
                (list '.then expr (list 'clojure.core/fn (vector sym)
                                        body))))
            body
            binding-pairs)))

Using this macro we can look async code more like sync code. Consider this puppeteer example:

(-> (.launch puppeteer)
      (.then (fn [browser]
               (-> (.newPage browser)
                   (.then (fn [page]
                            (-> (.goto page "https://clojure.org")
                                (.then #(.screenshot page #js{:path "screenshot.png"}))
                                (.catch #(js/console.log %))
                                (.then #(.close browser)))))))))

Using plet this becomes:

(plet [browser (.launch puppeteer)
       page (.newPage browser)
       _ (.goto page "https://clojure.org")
       _ (-> (.screenshot page #js{:path "screenshot.png"})
             (.catch #(js/console.log %)))]
      (.close browser))

See the puppeteer example for the full code.

Since v0.0.36, nbb includes promesa which is a library to deal with promises. The above plet macro is similar to promesa.core/let.

Startup time

$ time nbb -e '(+ 1 2 3)'
6
nbb -e '(+ 1 2 3)'   0.17s  user 0.02s system 109% cpu 0.168 total

The baseline startup time for a script is about 170ms seconds on my laptop. When invoked via npx this adds another 300ms or so, so for faster startup, either use a globally installed nbb or use $(npm bin)/nbb script.cljs to bypass npx.

Dependencies

NPM dependencies

Nbb does not depend on any NPM dependencies. All NPM libraries loaded by a script are resolved relative to that script. When using the Reagent module, React is resolved in the same way as any other NPM library.

Classpath

To load .cljs files from local paths or dependencies, you can use the --classpath argument. The current dir is added to the classpath automatically. So if there is a file foo/bar.cljs relative to your current dir, then you can load it via (:require [foo.bar :as fb]). Note that nbb uses the same naming conventions for namespaces and directories as other Clojure tools: foo-bar in the namespace name becomes foo_bar in the directory name.

To load dependencies from the Clojure ecosystem, you can use the Clojure CLI or babashka to download them and produce a classpath:

$ classpath="$(clojure -A:nbb -Spath -Sdeps '{:aliases {:nbb {:replace-deps {com.github.seancorfield/honeysql {:git/tag "v2.0.0-rc5" :git/sha "01c3a55"}}}}}')"

and then feed it to the --classpath argument:

$ nbb --classpath "$classpath" -e "(require '[honey.sql :as sql]) (sql/format {:select :foo :from :bar :where [:= :baz 2]})"
["SELECT foo FROM bar WHERE baz = ?" 2]

Currently nbb only reads from directories, not jar files, so you are encouraged to use git libs. Support for .jar files will be added later.

Current file

The name of the file that is currently being executed is available via nbb.core/*file* or on the metadata of vars:

(ns foo
  (:require [nbb.core :refer [*file*]]))

(prn *file*) ;; "/private/tmp/foo.cljs"

(defn f [])
(prn (:file (meta #'f))) ;; "/private/tmp/foo.cljs"

Reagent

Nbb includes reagent.core which will be lazily loaded when required. You can use this together with ink to create a TUI application:

$ npm install ink

ink-demo.cljs:

(ns ink-demo
  (:require ["ink" :refer [render Text]]
            [reagent.core :as r]))

(defonce state (r/atom 0))

(doseq [n (range 1 11)]
  (js/setTimeout #(swap! state inc) (* n 500)))

(defn hello []
  [:> Text {:color "green"} "Hello, world! " @state])

(render (r/as-element [hello]))

Promesa

Working with callbacks and promises can become tedious. Since nbb v0.0.36 the promesa.core namespace is included with the let and do! macros. An example:

(ns prom
  (:require [promesa.core :as p]))

(defn sleep [ms]
  (js/Promise.
   (fn [resolve _]
     (js/setTimeout resolve ms))))

(defn do-stuff
  []
  (p/do!
   (println "Doing stuff which takes a while")
   (sleep 1000)
   1))

(p/let [a (do-stuff)
        b (inc a)
        c (do-stuff)
        d (+ b c)]
  (prn d))
$ nbb prom.cljs
Doing stuff which takes a while
Doing stuff which takes a while
3

Also see API docs.

Js-interop

Since nbb v0.0.75 applied-science/js-interop is available:

(ns example
  (:require [applied-science.js-interop :as j]))

(def o (j/lit {:a 1 :b 2 :c {:d 1}}))

(prn (j/select-keys o [:a :b])) ;; #js {:a 1, :b 2}
(prn (j/get-in o [:c :d])) ;; 1

Most of this library is supported in nbb, except the following:

  • destructuring using :syms
  • property access using .-x notation. In nbb, you must use keywords.

See the example of what is currently supported.

Examples

See the examples directory for small examples.

Also check out these projects built with nbb:

API

See API documentation.

Migrating to shadow-cljs

See this gist on how to convert an nbb script or project to shadow-cljs.

Build

Prequisites:

  • babashka >= 0.4.0
  • Clojure CLI >= 1.10.3.933
  • Node.js 16.5.0 (lower version may work, but this is the one I used to build)

To build:

  • Clone and cd into this repo
  • bb release

Run bb tasks for more project-related tasks.

Download Details:
Author: borkdude
Download Link: Download The Source Code
Official Website: https://github.com/borkdude/nbb 
License: EPL-1.0

#node #javascript

Justyn  Ortiz

Justyn Ortiz

1599994800

Web Component Solutions: A Comparison

“Don’t repeat yourself.” Every programmer has this concept drilled into their head when first learning to code. Any time you have code you find yourself duplicating in several places, it’s time to abstract that code away into a class or a function. But how does this apply to user interfaces? How do you avoid re-writing the same HTML and CSS over and over again?

If you’re using a UI framework like Angular or a UI library like React, the answer is simple: you build a component. Components are bits of HTML, CSS, and JavaScript put together in a way that they can be easily reused.

But what if you’re not using Angular, React, Vue, or whatever else is the latest and greatest new JavaScript framework? What if you’re writing plain vanilla HTML, CSS, and JavaScript? Or what if you want to write a component that is framework-agnostic and can be used in any web app regardless of what it’s written in?

#javascript #development #web developement #html #salesforce #web components #lightning web components framework #stencil #ui frameworks

Aria Barnes

Aria Barnes

1622719015

Why use Node.js for Web Development? Benefits and Examples of Apps

Front-end web development has been overwhelmed by JavaScript highlights for quite a long time. Google, Facebook, Wikipedia, and most of all online pages use JS for customer side activities. As of late, it additionally made a shift to cross-platform mobile development as a main technology in React Native, Nativescript, Apache Cordova, and other crossover devices. 

Throughout the most recent couple of years, Node.js moved to backend development as well. Designers need to utilize a similar tech stack for the whole web project without learning another language for server-side development. Node.js is a device that adjusts JS usefulness and syntax to the backend. 

What is Node.js? 

Node.js isn’t a language, or library, or system. It’s a runtime situation: commonly JavaScript needs a program to work, however Node.js makes appropriate settings for JS to run outside of the program. It’s based on a JavaScript V8 motor that can run in Chrome, different programs, or independently. 

The extent of V8 is to change JS program situated code into machine code — so JS turns into a broadly useful language and can be perceived by servers. This is one of the advantages of utilizing Node.js in web application development: it expands the usefulness of JavaScript, permitting designers to coordinate the language with APIs, different languages, and outside libraries.

What Are the Advantages of Node.js Web Application Development? 

Of late, organizations have been effectively changing from their backend tech stacks to Node.js. LinkedIn picked Node.js over Ruby on Rails since it took care of expanding responsibility better and decreased the quantity of servers by multiple times. PayPal and Netflix did something comparative, just they had a goal to change their design to microservices. We should investigate the motivations to pick Node.JS for web application development and when we are planning to hire node js developers. 

Amazing Tech Stack for Web Development 

The principal thing that makes Node.js a go-to environment for web development is its JavaScript legacy. It’s the most well known language right now with a great many free devices and a functioning local area. Node.js, because of its association with JS, immediately rose in ubiquity — presently it has in excess of 368 million downloads and a great many free tools in the bundle module. 

Alongside prevalence, Node.js additionally acquired the fundamental JS benefits: 

  • quick execution and information preparing; 
  • exceptionally reusable code; 
  • the code is not difficult to learn, compose, read, and keep up; 
  • tremendous asset library, a huge number of free aides, and a functioning local area. 

In addition, it’s a piece of a well known MEAN tech stack (the blend of MongoDB, Express.js, Angular, and Node.js — four tools that handle all vital parts of web application development). 

Designers Can Utilize JavaScript for the Whole Undertaking 

This is perhaps the most clear advantage of Node.js web application development. JavaScript is an unquestionable requirement for web development. Regardless of whether you construct a multi-page or single-page application, you need to know JS well. On the off chance that you are now OK with JavaScript, learning Node.js won’t be an issue. Grammar, fundamental usefulness, primary standards — every one of these things are comparable. 

In the event that you have JS designers in your group, it will be simpler for them to learn JS-based Node than a totally new dialect. What’s more, the front-end and back-end codebase will be basically the same, simple to peruse, and keep up — in light of the fact that they are both JS-based. 

A Quick Environment for Microservice Development 

There’s another motivation behind why Node.js got famous so rapidly. The environment suits well the idea of microservice development (spilling stone monument usefulness into handfuls or many more modest administrations). 

Microservices need to speak with one another rapidly — and Node.js is probably the quickest device in information handling. Among the fundamental Node.js benefits for programming development are its non-obstructing algorithms.

Node.js measures a few demands all at once without trusting that the first will be concluded. Many microservices can send messages to one another, and they will be gotten and addressed all the while. 

Versatile Web Application Development 

Node.js was worked in view of adaptability — its name really says it. The environment permits numerous hubs to run all the while and speak with one another. Here’s the reason Node.js adaptability is better than other web backend development arrangements. 

Node.js has a module that is liable for load adjusting for each running CPU center. This is one of numerous Node.js module benefits: you can run various hubs all at once, and the environment will naturally adjust the responsibility. 

Node.js permits even apportioning: you can part your application into various situations. You show various forms of the application to different clients, in light of their age, interests, area, language, and so on. This builds personalization and diminishes responsibility. Hub accomplishes this with kid measures — tasks that rapidly speak with one another and share a similar root. 

What’s more, Node’s non-hindering solicitation handling framework adds to fast, letting applications measure a great many solicitations. 

Control Stream Highlights

Numerous designers consider nonconcurrent to be one of the two impediments and benefits of Node.js web application development. In Node, at whatever point the capacity is executed, the code consequently sends a callback. As the quantity of capacities develops, so does the number of callbacks — and you end up in a circumstance known as the callback damnation. 

In any case, Node.js offers an exit plan. You can utilize systems that will plan capacities and sort through callbacks. Systems will associate comparable capacities consequently — so you can track down an essential component via search or in an envelope. At that point, there’s no compelling reason to look through callbacks.

 

Final Words

So, these are some of the top benefits of Nodejs in web application development. This is how Nodejs is contributing a lot to the field of web application development. 

I hope now you are totally aware of the whole process of how Nodejs is really important for your web project. If you are looking to hire a node js development company in India then I would suggest that you take a little consultancy too whenever you call. 

Good Luck!

Original Source

#node.js development company in india #node js development company #hire node js developers #hire node.js developers in india #node.js development services #node.js development

Why Use WordPress? What Can You Do With WordPress?

Can you use WordPress for anything other than blogging? To your surprise, yes. WordPress is more than just a blogging tool, and it has helped thousands of websites and web applications to thrive. The use of WordPress powers around 40% of online projects, and today in our blog, we would visit some amazing uses of WordPress other than blogging.
What Is The Use Of WordPress?

WordPress is the most popular website platform in the world. It is the first choice of businesses that want to set a feature-rich and dynamic Content Management System. So, if you ask what WordPress is used for, the answer is – everything. It is a super-flexible, feature-rich and secure platform that offers everything to build unique websites and applications. Let’s start knowing them:

1. Multiple Websites Under A Single Installation
WordPress Multisite allows you to develop multiple sites from a single WordPress installation. You can download WordPress and start building websites you want to launch under a single server. Literally speaking, you can handle hundreds of sites from one single dashboard, which now needs applause.
It is a highly efficient platform that allows you to easily run several websites under the same login credentials. One of the best things about WordPress is the themes it has to offer. You can simply download them and plugin for various sites and save space on sites without losing their speed.

2. WordPress Social Network
WordPress can be used for high-end projects such as Social Media Network. If you don’t have the money and patience to hire a coder and invest months in building a feature-rich social media site, go for WordPress. It is one of the most amazing uses of WordPress. Its stunning CMS is unbeatable. And you can build sites as good as Facebook or Reddit etc. It can just make the process a lot easier.
To set up a social media network, you would have to download a WordPress Plugin called BuddyPress. It would allow you to connect a community page with ease and would provide all the necessary features of a community or social media. It has direct messaging, activity stream, user groups, extended profiles, and so much more. You just have to download and configure it.
If BuddyPress doesn’t meet all your needs, don’t give up on your dreams. You can try out WP Symposium or PeepSo. There are also several themes you can use to build a social network.

3. Create A Forum For Your Brand’s Community
Communities are very important for your business. They help you stay in constant connection with your users and consumers. And allow you to turn them into a loyal customer base. Meanwhile, there are many good technologies that can be used for building a community page – the good old WordPress is still the best.
It is the best community development technology. If you want to build your online community, you need to consider all the amazing features you get with WordPress. Plugins such as BB Press is an open-source, template-driven PHP/ MySQL forum software. It is very simple and doesn’t hamper the experience of the website.
Other tools such as wpFoRo and Asgaros Forum are equally good for creating a community blog. They are lightweight tools that are easy to manage and integrate with your WordPress site easily. However, there is only one tiny problem; you need to have some technical knowledge to build a WordPress Community blog page.

4. Shortcodes
Since we gave you a problem in the previous section, we would also give you a perfect solution for it. You might not know to code, but you have shortcodes. Shortcodes help you execute functions without having to code. It is an easy way to build an amazing website, add new features, customize plugins easily. They are short lines of code, and rather than memorizing multiple lines; you can have zero technical knowledge and start building a feature-rich website or application.
There are also plugins like Shortcoder, Shortcodes Ultimate, and the Basics available on WordPress that can be used, and you would not even have to remember the shortcodes.

5. Build Online Stores
If you still think about why to use WordPress, use it to build an online store. You can start selling your goods online and start selling. It is an affordable technology that helps you build a feature-rich eCommerce store with WordPress.
WooCommerce is an extension of WordPress and is one of the most used eCommerce solutions. WooCommerce holds a 28% share of the global market and is one of the best ways to set up an online store. It allows you to build user-friendly and professional online stores and has thousands of free and paid extensions. Moreover as an open-source platform, and you don’t have to pay for the license.
Apart from WooCommerce, there are Easy Digital Downloads, iThemes Exchange, Shopify eCommerce plugin, and so much more available.

6. Security Features
WordPress takes security very seriously. It offers tons of external solutions that help you in safeguarding your WordPress site. While there is no way to ensure 100% security, it provides regular updates with security patches and provides several plugins to help with backups, two-factor authorization, and more.
By choosing hosting providers like WP Engine, you can improve the security of the website. It helps in threat detection, manage patching and updates, and internal security audits for the customers, and so much more.

Read More

#use of wordpress #use wordpress for business website #use wordpress for website #what is use of wordpress #why use wordpress #why use wordpress to build a website

Kabanda  Nat

Kabanda Nat

1624094899

[Part 2]: Using Lightning Web Components to Create Progressive Web Apps

When a server sends a push notification to a subscribed user, it needs to authenticate itself as the same server to which the user subscribed. To do this, there is an entire spec (called the VAPID spec) that dictates how this authentication works. Fortunately for us, the web-push package helps to abstract away most of these low-level details.

The one thing we do need to do, however, is generate a VAPID public/private key pair, and store it in a .env file so we can access those keys as environment variables.

#web dev #progressive #web apps #lightning web #components