u/Own_Grand1767

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Today I got to know about polyfill by using this we can add and modify a function in javascript.

Like we can built custom map function

Array.prototype.myMap = function (callback){

const res = [];

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

res.push(callback(this[i]))

}

return res;

}

const arr = [1,2,3,4]

const newArr=arr.myMap((ele)=>ele*2)

console.log(newArr)