Polyfills In Javascript !

JavaScript evolves, new features are added to the language to simplify development and improve performance. However, not all browsers—especially older ones—support these new features.

What Is a Polyfill?

A polyfill is a piece of JavaScript code that implements a feature on web browsers that do not natively support it. Think of it as a fallback that "fills in the gap." Array.prototype.includes(), a polyfill can replicate that functionality.

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Why Use Polyfills?

• To ensure cross compatibility with older browsers

• To use modern JavaScript features without worrying about browser support

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Example

(!Array.prototype.includes) {
  Array.prototype.includes = function (element) {
    return this.indexOf(element) !== -1;
  };
}

Polyfill and its advantage ✌️

Wider Compatibliity : It’s help to add modern features and method in older browser that all browser compatiable working as same.

Solutions make easy : It has various techniques to add features and it is not limited.

Modern Things to do : It’s added modern things codes which compatiable with backend easily.

Let’s create own map method

const numValue = [1, 2, 3, 4, 5];
const multiNum = numValue.map(x => x * 2); // New Array with multi [2, 4, 6, 8, 10]
const arrayIndex = numValue.map((x, index) => x * index); // [0, 2, 6, 12, 20]

if(Array.prototype.map()){
    Array.prototype.myMap = function(param) {
       let output = [];
       let arr = this;
       for(let i = 0; i < arr.length; i++) {
          output.push(param(arr[i], i));
       }
       return output;
    }
}

In the above myMap method, first at all let cheking method exist or not after then use Array.prototype.nameOfMethod. Then create a function which helps to get my logic into code. Use an empty array which hold the output from current array after run up the with for loop iterate the each element and push use array push() method into the output variable. After that end of the with returning the output.

Best Practices for Using Polyfills

Features Checking Exist or Not : before implementing any feature let look at first.

Making Code Better Readiblity : Make your code for better use of version and readiblity

Overload : Use which are required not make it overloaded for your application.

Make With Optimize : try use library for better optmize before writting polyfills.

Conclution

Polyfills are the better way to add modern browser feature’s into olde one. Which help to run and perform cross browser feature with breaking.