How to use Polyfill in JavaScript ?

A polyfill in JavaScript is a script that adds modern features to older browsers that do not natively support them. To use it, include the polyfill script in your HTML or install it via a package manager, ensuring compatibility with older environments.

Polyfill and its features

• Broad Compatibility: Polyfills address gaps in browser support for modern JavaScript features, ensuring older browsers can run newer code.
• Wide Range of Solutions: Polyfills can be implemented using various techniques, not limited to JavaScript alone.
• Enhancing Functionality: Polyfills add missing features, such as ES6+ syntax and built-in functions, to environments lacking support.
• Transpiler Integration: Polyfills are often used alongside transpilers like Babel to convert modern code into a backward-compatible format.

In older browsers, the following features require polyfill support by explicitly defining the functions:

Promises, Array.from, Array.includes, Array.of, Map, Set, Symbol, object.values, etc

How to use polyfill in javascript? 

We will explore how polyfill works in node.js in this article. 

Approach: We will use promises. We will be writing the promises in ES6 code and then converting it into ES5 code to avoid the incompatibility issues of older browsers. We will then add this ES5 code babel polyfill file from our node modules to our index.html file to run the code in our browser. 

Step 1: Environment setup

A Babel transpiler is a free, open-source tool that converts ECMAScript 2015 (ES6) code to a backward-compatible version of JavaScript that can run on old and new browsers.  

We'll set up our project and look at the Babel polyfill.

• Make sure you have Node.js installed on your machine to run Babel polyfill.
• Create a new project directory and run the following command in your terminal to get started:npm init -y 

• Run the following command to install the babel cli, core and preset.

npm install @babel/cli @babel/core @babel/preset-env --save-dev

Package.json: It will look like this.

Conclusion

Polyfills are essential for maintaining cross-browser compatibility when using modern JavaScript features. They help ensure that your code works seamlessly across both modern and older environments, providing a consistent user experience