Introduction to unit testing in JS

If you're new to programming or you're just a hobby programmer and haven't ever done any kind of open source project then you might feel a bit skeptical about the idea of&nbsp;<strong>testing</strong>&nbsp;your code. If you indeed are, then in this article, let me convince you that doing&nbsp;<strong>unit tests</strong>&nbsp;for your code and testing it, in general, is a good practice to follow. Then we'll learn/revise a bit about code testing and finally explore best tools to do unit tests. Enjoy! ūüėČ

If you're new to programming or you're just a hobby programmer and haven't ever done any kind of open source project then you might feel a bit skeptical about the idea of¬†testing¬†your code. If you indeed are, then in this article, let me convince you that doing¬†unit tests¬†for your code and testing it, in general, is a good practice to follow. Then we'll learn/revise a bit about code testing and finally explore best tools to do unit tests. Enjoy! ūüėČ

Why testing?

At the beginning let's talk about why testing is important. When you're developing any kind of app or tool (especially open-source) then tests should be your allies. Consider the¬†quality¬†that they bring. When your tests cover all possible exceptions and cases in your code, you can be sure that it won't fail you in the future. That's yet another reason for testing -¬†assurance. Having tests that cover your entire code-base kept up-to-date allows you to continuously check it for any errors. It makes you sure that everything is fine. If you haven't done any project that needs to be managed by a number of people or needs to serve others (OSS) then you might not really take this whole assurance as a thing. But believe me, it's really important. You can never be sure of¬†wellness¬†of your code without any¬†warranty. ūüėē Last but not least we have the advantage of¬†documentation. Believe it or not, properly done tests can sometimes deliver an even better understanding of how to use a particular piece of code than the entire page of text. Just think about it. You have tests that your code passes. This way you have information about how to use the given code and what its outcome is. So, as you can see there are many reasons to start testing your code, thus if you haven't already, it's time to do some testing!

Kinds of tests

If I managed to convince you to do testing, then I'm really happy. ūüéČ But the size of the world of code testing can feel a bit overwhelming at the beginning. There are so many terms, concepts, ideologies and tools, and libraries to know about. Let's give it some structure then. First things first, you have to know what kind of tests you're doing, so that you can later choose the right tools for the job. There are 3 main¬†types¬†of tests, divided by the reason they exist.

  • Unit tests¬†- Unit testing allows you to test a really¬†specific aspect¬†of your code, e.g. one function against expected outcome. Here it's really important for your tests to cover all the code that you have, feature by feature. These are the main focal point of this post.
  • Integration tests¬†- Test different parts of your code e.g. components to work as they should. You should also check the way they work together i.e.¬†structural integrity. Side effects are also really important to check. You have to know if there aren't any functions calls and etc. that you didn't plan.
  • Functional tests¬†- I think the name¬†UI tests¬†explains the purpose of these a little better. With functional tests, you check your final product e.g. web app in a specified¬†environment, usually a browser. Here comes the concept of headless browsers, where you execute your test in a browser without visible UI by controlling it with different API calls. It might seem a little awkward at first, but it's a very useful technique, especially for saving some time required by UI and other processes, that are not present in headless mode.
Terminology

Now, that you know a bit more about different kinds of test and what unit tests exactly are, I think it's a good idea to talk a little bit about basic concepts and terms when it comes to testing.

I'd like to start by explaining the TDD and BDD shortcuts that you might have already seen somewhere before but didn't pay much attention to. As these can be seen as basic guidelines when structuring and writing your tests.

Test-Driven-Development (or TDD for short) is a process of developing your software while basing on tests. It's like a cycle, a loop - every time you want to add a feature, you first write your tests (which will obviously fail at this point), then you write the actual code, that fulfills these tests, and then you test again to check that. Your development is based on tests. Pretty interesting idea, won't you agree?

As for¬†Behavior-Driven-Development¬†(BDD), it's yet another ideology, which in fact is based upon TDD. But, the name might not be as self-explanatory as it was with the first one. It can be seen as TDD with some better, additional guidelines. Here, our development is driven not by test specifically, but by behavior, specification, which in fact are tests anyway. ūüėā They are just better described, using¬†pure English. This allows your tests to be much better documented and thus more¬†readable. That's why libraries adopt this way of doing tests more often than TDD.

With the knowledge of these 2 trends that are so important when it comes to testing, it's time to explore some terms, explained just as BDD suggests, in English. ūüėČ

  • Assertion functions¬†- functions that we use to¬†test¬†our code against expected output. In Jest and many other unit testing libraries they look like this:
expect(value).toBeTruthy()
  • Code coverage¬†- indicate how big part of our code the tests cover. These are some incredibly useful stats, which can be an additional feature to consider when choosing your next testing library of choice. Of course, there are¬†standalone tools¬†for this, but having everything in one bundle is much more comfortable.
  • Environment¬†- generally a (headless)¬†browser¬†or¬†something similar¬†for your functional tests. We're not going to dig into this one, but there are some nice options available here as well. ūüėĄ
  • Mocks¬†- also called¬†fakes, are used to fake certain behaviors to later use them in tests, to provide reliable input/output checks even without different features implemented in a realistic manner.
  • Spies¬†- provide¬†information¬†about functions. By using them you can know e.g. how many times, when and with what arguments a function was called. They are possibly the best way to check for side effects.
  • Stubs¬†- alternatively called¬†dubs, give you the ability to replace chosen function with something different, to test expected functionality and behavior.
  • Snapshot testing¬†- a way of testing, based on comparing output data with an already saved copy (snapshot).

With this, you should have a basic understanding of ways of testing and functionalities that you would expect from your library-of-choice. As here I'm focusing only on unit tests, be sure to check out some links in above-listed terms for tools that provide given functionality in a standalone package.

Unit testing

With theory out of the way, it's time to do some testing - unit testing! But first, let's choose the¬†best tool¬†for the job. Here comes the list of some of the best libraries and tools for unit testing & more. ūüĒ•

Jest
test('adds 1 + 2 to equal 3', () => {
  expect(1 + 2).toBe(3);
});

Jest is my personal go-to when it comes to unit testing. Started by guys from Facebook, it has been well battle-tested with a number of popular libraries, such as React itself. It provides almost all features required for high-quality unit testing. Readable assertion functions, great coverage reports, mocking API, parallel test runner and general ease-of-use makes this library one of the best choices available on the market right now, especially for BDD. Aside from that, a great community and support and well-written documentation are very much noticeable.

Mocha
var assert = require('assert');
describe('Array', function() {
  describe('#indexOf()', function() {
    it('should return -1 when the value is not present', function() {
      assert.equal([1,2,3].indexOf(4), -1);
    });
  });
});

Mocha is yet another library, with the goal of making testing fun and simple. Following BDD ideology, it has well-design descriptive API. Also, Mocha is different when it comes to its architecture. It provides developers with minimal, flexible setup, allowing them to extend it with other custom libraries, responsible for different tasks. With Mocha, you can use any assertion library you want (it doesn't have its own), including the NodeJS built-in one or Chai. Its API might feel a little similar to Jest's with some small differences. Because of its architecture, Mocha lacks features that Jest has built-in. We're talking about code coverage and more importantly parallel test runner (Mocha runs tests on one process only). Well, where it lacks in functionality, Mocha makes up in visuals with a great choice of tests progress reporters (a feature supported by Jest too). But, as I said, Mocha is for those you like to have their own configurable setups. Besides that, its docs might feel less polished that Jest's but they defiantly exhaust the topic.

Jasmine
describe("A suite is just a function", function() {
  var a;
  it("and so is a spec", function() {
    a = true;
    expect(a).toBe(true);
  });
});

Jasmine might be a bit older than some of its competitors on this list. It's advertised as batteries-included, trying to provide every feature that developers would possibly need. Thus, Jasmine has assertion functionality built-in with expect style implementation. With that comes other built-in features, such as spies, mocks, reporters etc. Also, if you're doing some development with Ruby or Python, you might find it comfortable to use the same library, as Jasmine has official support for those two. As for the docs, they cover all the topics well, but their structure didn't really impress me.

Tape
var test = require('tape');

test('timing test', function (t) {
t.plan(1);
var start = Date.now();

setTimeout(function () {
    t.equal(Date.now() - start, 100);
}, 100);

});

Tape is, again, minimal and flexible library for doing tests for NodeJS and browser. Its API is a bit different than the others' but still readable, with the same ideology in mind. Everything you need to know about it has its place in a single README file. And... it has pretty support for a great number of TAP reporters which is always an advantage.

AVA
import test from 'ava';

test('foo', t => {
t.pass();
});

test('bar', async t => {
const bar = Promise.resolve('bar');
t.is(await bar, 'bar');
});

AVA is a testing library with built-in assertion functions and great focus on async tests. It has simple API (just like other BDD tools) and the ability to run tests in parallel. Just like Tape (which it's inspired by), it has no implicit globals. In addition to that, it has Babel v7 built-in, so that you can write your tests in ES-Next without any additional configuration. All its documentation can be found on its GitHub repo.

Intern

Intern is a TDD/BDD testing framework and tests runner for JavaScript, as well as TypeScript. It allows you to perform both unit and functional tests. It uses Chai as the assertion library and Istanbul to generate your code coverage stats. It can also run your tests concurrently. Generally speaking, it's an extendable framework for doing tests. Did I mention that it has very good, comprehensive documentation?

Cucumber.js
Feature: Simple maths
In order to do maths
As a developer
I want to increment variables

Scenario: easy maths
Given a variable set to 1
When I increment the variable by 1
Then the variable should contain 2

Scenario Outline: much more complex stuff
Given a variable set to <var>
When I increment the variable by <increment>
Then the variable should contain <result>

Examples:
  | var | increment | result |
  | 100 |         5 |    105 |
  |  99 |      1234 |   1333 |
  |  12 |         5 |     18 |

Cucumber.js¬†is another unit testing tool, but this time a little different... It allows you to write your tests in¬†plain language. Basically what you do is you write your test in a structured text format using some¬†keywords¬†like¬†Scenario,¬†Given,¬†When¬†etc. and then in your code you define what each step written in plain language should do to run expected tests. I haven't ever used such an approach, so I won't tell you how comfortable it is in real use. But, at least it seems interesting. ūüėÖ

Testing, testing...

So, that's it for my list of best tools for doing unit tests. Of course, if I missed an entry worth including in this list, let me know about that down in the comments. Keep in mind that I've covered unit testing only in this list, so no tools for integration, functional or end-to-end (covering every type of tests) testing here. I think it would be too much for one article. It's better to explore smaller topics one-by-one IMHO. In fact, by doing that article I learned a lot too. I'm definitely not a testing expert, but at least now I've got some new knowledge. I hope this post also helped you in your journey with code tests. That's all for now.


By : Areknawo



JavaScript Tutorial: if-else Statement in JavaScript

JavaScript Tutorial: if-else Statement in JavaScript

This JavaScript tutorial is a step by step guide on JavaScript If Else Statements. Learn how to use If Else in javascript and also JavaScript If Else Statements. if-else Statement in JavaScript. JavaScript's conditional statements: if; if-else; nested-if; if-else-if. These statements allow you to control the flow of your program's execution based upon conditions known only during run time.

Decision Making in programming is similar to decision making in real life. In programming also we face some situations where we want a certain block of code to be executed when some condition is fulfilled.
A programming language uses control statements to control the flow of execution of the program based on certain conditions. These are used to cause the flow of execution to advance and branch based on changes to the state of a program.

JavaScript’s conditional statements:

  • if
  • if-else
  • nested-if
  • if-else-if

These statements allow you to control the flow of your program’s execution based upon conditions known only during run time.

  • if: if statement is the most simple decision making statement. It is used to decide whether a certain statement or block of statements will be executed or not i.e if a certain condition is true then a block of statement is executed otherwise not.
    Syntax:
if(condition) 
{
   // Statements to execute if
   // condition is true
}

Here, condition after evaluation will be either true or false. if statement accepts boolean values ‚Äď if the value is true then it will execute the block of statements under it.
If we do not provide the curly braces ‚Äė{‚Äė and ‚Äė}‚Äô after if( condition ) then by default if statement will consider the immediate one statement to be inside its block. For example,

if(condition)
   statement1;
   statement2;

// Here if the condition is true, if block 
// will consider only statement1 to be inside 
// its block.

Flow chart:

Example:

<script type = "text/javaScript"> 

// JavaScript program to illustrate If statement 

var i = 10; 

if (i > 15) 
document.write("10 is less than 15"); 

// This statement will be executed 
// as if considers one statement by default 
document.write("I am Not in if"); 

< /script> 

Output:

I am Not in if
  • if-else: The if statement alone tells us that if a condition is true it will execute a block of statements and if the condition is false it won‚Äôt. But what if we want to do something else if the condition is false. Here comes the else statement. We can use the else statement with if statement to execute a block of code when the condition is false.
    Syntax:
if (condition)
{
    // Executes this block if
    // condition is true
}
else
{
    // Executes this block if
    // condition is false
}


Example:

<script type = "text/javaScript"> 

// JavaScript program to illustrate If-else statement 

var i = 10; 

if (i < 15) 
document.write("10 is less than 15"); 
else
document.write("I am Not in if"); 

< /script> 

Output:

i is smaller than 15
  • nested-if A nested if is an if statement that is the target of another if or else. Nested if statements means an if statement inside an if statement. Yes, JavaScript allows us to nest if statements within if statements. i.e, we can place an if statement inside another if statement.
    Syntax:
if (condition1) 
{
   // Executes when condition1 is true
   if (condition2) 
   {
      // Executes when condition2 is true
   }
}

Example:

<script type = "text/javaScript"> 

// JavaScript program to illustrate nested-if statement 

var i = 10; 

if (i == 10) { 

// First if statement 
if (i < 15) 
	document.write("i is smaller than 15"); 

// Nested - if statement 
// Will only be executed if statement above 
// it is true 
if (i < 12) 
	document.write("i is smaller than 12 too"); 
else
	document.write("i is greater than 15"); 
} 
< /script> 

Output:

i is smaller than 15
i is smaller than 12 too
  • if-else-if ladder Here, a user can decide among multiple options.The if statements are executed from the top down. As soon as one of the conditions controlling the if is true, the statement associated with that if is executed, and the rest of the ladder is bypassed. If none of the conditions is true, then the final else statement will be executed.
if (condition)
    statement;
else if (condition)
    statement;
.
.
else
    statement;


Example:

<script type = "text/javaScript"> 
// JavaScript program to illustrate nested-if statement 

var i = 20; 

if (i == 10) 
document.wrte("i is 10"); 
else if (i == 15) 
document.wrte("i is 15"); 
else if (i == 20) 
document.wrte("i is 20"); 
else
document.wrte("i is not present"); 
< /script> 

Output:

i is 20

How to Retrieve full Profile of LinkedIn User using Javascript

How to Retrieve full Profile of LinkedIn User using Javascript

I am trying to retrieve the full profile (especially job history and educational qualifications) of a linkedin user via the Javascript (Fetch LinkedIn Data Using JavaScript)

Here we are fetching LinkedIn data like Username, Email and other fields using JavaScript SDK.

Here we have 2 workarounds.

  1. Configuration of linkedIn developer api
  2. Javascript Code to fetch records

Configuration of linkedIn developer api

In order to fetch records, first we need to create developer api in linkedin which will act as token/identity while fetching data from other linkedin accounts.

So to create api, navigate to https://linkedin.com/developer/apps and click on 'Create Application'.

After navigating, fill in details like name, description and other required fields and then submit.

As we submit, it will create Client ID and Client Secret shown below, which we will be using in our code while communicating to fetch records from other LinkedIn account.

Note: We need to provide localhost Url here under Oauth 2.0. I am using my localhost, but you can probably use other production URLs under Oauth 2.0 where your app is configured. It will make your api  consider the Url as trusted which fetching records.

Javascript Code to fetch records

For getting user details like first name, last name,User image can be written as,

<script type="text/javascript" src="https://platform.linkedin.com/in.js">  
    api_key: XXXXXXX //Client ID  
    onLoad: OnLinkedInFrameworkLoad //Method that will be called on page load  
    authorize: true  
</script>  
<script type="text/javascript">  
    function OnLinkedInFrameworkLoad() {  
        IN.Event.on(IN, "auth", OnLinkedInAuth);  
    }  
  
    function OnLinkedInAuth() {  
        IN.API.Profile("me").result(ShowProfileData);  
    }  
  
    function ShowProfileData(profiles) {  
        var member = profiles.values[0];  
        var id = member.id;  
        var firstName = member.firstName;  
        var lastName = member.lastName;  
        var photo = member.pictureUrl;  
        var headline = member.headline;  
        //use information captured above  
        var stringToBind = "<p>First Name: " + firstName + " <p/><p> Last Name: " + lastName + "<p/><p>User ID: " + id + " and Head Line Provided: " + headline + "<p/>"  
        document.getElementById('profiles').innerHTML = stringToBind;  
    }  
</script>    

Kindly note we need to include 'https://platform.linkedin.com/in.js' as src under script type as it will act on this Javascript SDK provided by Linkedin.

In the same way we can also fetch records of any organization with the companyid as keyword.

<head>  
    <script type="text/javascript" src="https://platform.linkedin.com/in.js">  
        api_key: XXXXXXX ////Client ID  
        onLoad: onLinkedInLoad  
        authorize: true  
    </script>  
</head>  
  
<body>  
    <div id="displayUpdates"></div>  
    <script type="text/javascript">  
        function onLinkedInLoad() {  
            IN.Event.on(IN, "auth", onLinkedInAuth);  
            console.log("On auth");  
        }  
  
        function onLinkedInAuth() {  
            var cpnyID = XXXXX; //the Company ID for which we want updates  
            IN.API.Raw("/companies/" + cpnyID + "/updates?event-type=status-update&start=0&count=10&format=json").result(displayCompanyUpdates);  
            console.log("After auth");  
        }  
  
        function displayCompanyUpdates(result) {  
            var div = document.getElementById("displayUpdates");  
            var el = "<ul>";  
            var resValues = result.values;  
            for (var i in resValues) {  
                var share = resValues[i].updateContent.companyStatusUpdate.share;  
                var isContent = share.content;  
                var isTitled = isContent,  
                    isLinked = isContent,  
                    isDescription = isContent,  
                    isThumbnail = isContent,  
                    isComment = isContent;  
                if (isTitled) {  
                    var title = isContent.title;  
                } else {  
                    var title = "News headline";  
                }  
                var comment = share.comment;  
                if (isLinked) {  
                    var link = isContent.shortenedUrl;  
                } else {  
                    var link = "#";  
                }  
                if (isDescription) {  
                    var description = isContent.description;  
                } else {  
                    var description = "No description";  
                }  
                /* 
                if (isThumbnailz) { 
                var thumbnailUrl = isContent.thumbnailUrl; 
                } else { 
                var thumbnailUrl = "http://placehold.it/60x60"; 
                } 
                */  
                if (share) {  
                    var content = "<a target='_blank' href=" + link + ">" + comment + "</a><br>";  
                    //el += "<li><img src='" + thumbnailUrl + "' alt=''>" + content + "</li>";  
                    el += "<li><div>" + content + "</div></li>";  
                }  
                console.log(share);  
            }  
            el += "</ul>";  
            document.getElementById("displayUpdates").innerHTML = el;  
        }  
    </script>  
</body>  

We can get multiple metadata while fetching records for any any organization. We can get company updates as shown below.

Conclusion

We can also fetch any company specific data like company job updates/post, total likes, comments, and number of views along with a lot of metadata we can fetch which I have shown below.

Thank you for reading !

7 Best Javascript Iframe Libraries

7 Best Javascript Iframe Libraries

Iframes let you build user experiences into embeddable ‚Äėcross-domain components‚Äô, which let users interact with other sites without being redirected. I have compiled 7 best Javascript iframe libraries.

Iframes let you build user experiences into embeddable ‚Äėcross-domain components‚Äô, which let users interact with other sites without being redirected. I have compiled 7 best Javascript iframe libraries.

1. Zoid

A cross-domain component toolkit, supporting:

  • Render an iframe or popup on a different domain, and pass down props, including objects and functions
  • Call callbacks natively from the child window without worrying about post-messaging or cross-domain restrictions
  • Create and expose components to share functionality from your site to others!
  • Render your component directly as a React, Vue or Angular component!
    It's 'data-down, actions up' style components, but 100% cross-domain using iframes and popups!

Download


2. Postmate

Postmate is a promise-based API built on postMessage. It allows a parent page to speak with a child iFrame across origins with minimal effort.

Download


3. Iframe Resizer

Keep same and cross domain iFrames sized to their content with support for window/content resizing, in page links, nesting and multiple iFrames

Demo

Download


4. Iframely

Embed proxy. Supports over 1800 domains via custom parsers, oEmbed, Twitter Cards and Open Graph

Demo

Download


5. React Frame component

This component allows you to encapsulate your entire React application or per component in an iFrame.

Demo

Download


6. Seamless.js

A seamless iframe makes it so that visitors are unable to distinguish between content within the iframe and content beside the iframe. Seamless.js is a JavaScript library (with no dependencies) that makes working with iframes easy by doing all the seamless stuff for you automatically.

Demo

Download


7. Porthole

A proxy to safely communicate to cross-domain iframes in javascript

Demo

Download


Thank for read!