Introduction

In this blog, you are going to learn how JavaScript built-in methods work internally. You will also learn how developers make JavaScript compatible with older browsers using polyfills.

What are polyfills :

A polyfill is a piece of JavaScript code that adds support for modern features in older browsers that don’t support them natively.

If the browser doesn’t have a feature, we create it ourselves.

Example :

Let's take an example that older browser doesn't support Array.prototype.includes.

We write polyfill like this

if (!Array.prototype.includes) {

Array.prototype.includes = function (value) {

for (let i = 0; i < this.length; i++) {

if (this[i] === value) {

return true;

}

}

return false;

};

}

What are Built-in methods?

Built-in methods are predefined functions provided by the JavaScript runtime environment that are used to perform specific tasks. We don’t need to write the logic from scratch.…