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  1. 1

    Writing unit test cases in JavaScript ensures that individual functions or modules work as expected. Two of the most popular tools for this are Jest and Mocha with Chai.

    Using Jest Jest is an all-in-one testing framework by Facebook, widely used for JavaScript and React projects. It has built-in assertions and requires minimal setup.

    Example:

    // math.js
    function add(a, b) {
    return a + b;
    }
    module.exports = add;

    // math.test.js
    const add = require('./math');

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

    Setup & Run:

    npm install --save-dev jest
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    In package.json:

    "scripts": { "test": "jest" }
    Copied!

    Run:

    npm test
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    Using Mocha and Chai Mocha is a flexible test runner, and Chai is an assertion library that works well with it.

    Example:

    // math.js
    function add(a, b) {
    return a + b;
    }
    module.exports = add;

    // math.test.js
    const add = require('./math');
    const { expect } = require('chai');

    describe('Addition function', () => {
    it('should add 1 and 2 to get 3', () => {
    expect(add(1, 2)).to.equal(3);
    });
    });
    Copied!
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  2. GeeksForGeeks
    https://www.geeksforgeeks.org › javascript › how-to...

    How to Start Unit Testing to a JavaScript Code? - GeeksforGeeks

    Aug 5, 2025 · For JavaScript, unit testing can be especially valuable given the dynamic nature of the language. This guide will introduce you to the two popular approaches to unit testing in JavaScript …

    • For JavaScript, unit testing can be especially valuable given the dynamic nature of the language. This guide will introduce you to the two popular approaches to …

    See results only from geeksforgeeks.org
  3. FreeCodecamp
    https://www.freecodecamp.org › news › how-to-start-unit-testing-javascript

    How to Start Unit Testing Your JavaScript Code - freeCodeCamp.org

    Learn the benefits of unit testing and how to use Jest, a popular JavaScript testing framework. Follow the steps to write your first unit test for a simple function and see th…

    Before we dive into unit testing specifics, I want to do a quick run through of the different types of tests. There is often some confusion around them and I'm not surprised. Sometimes the line between them is quite thin.
    See more on freecodecamp.org
  4. Microsoft Learn
    https://learn.microsoft.com › en-us › visualstudio...

    Unit testing JavaScript and TypeScript in Visual Studio

    Sep 23, 2025 · You can write and run unit tests in Visual Studio using some of the more popular JavaScript frameworks without the need to switch to a command prompt. Both Node.js and ASP.NET …

  5. Medium
    https://medium.com › @karim.m.fayed › unit-testing-in...

    Unit Testing in JavaScript/TypeScript with Jest - Medium

    Apr 15, 2025 · Unit testing is the process of testing individual units of code — typically functions or methods — in isolation from the rest of the system. A “unit” …

  6. Jest
    https://jestjs.io

    Jest · Delightful JavaScript Testing

    Jest is a JavaScript testing framework designed to ensure correctness of any JavaScript codebase. It allows you to write tests with an approachable, familiar …

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