Create functionality of map() using pure Javascript

Question

Nikhil Upadhyay · Accepted Answer

if (!Array.prototype.customMap) {
    Array.prototype.customMap = function (callback) {
        let index,
            len = this.length;
        const newArray = [];
        for (index = 0; index < len; index++) {
            newArray.push(callback(this[index], index, this));
        }
        return newArray;
    }
}
const doubleArrayElem = [1,2,3,4,5,6].customMap(function (elem, index, arr) {
    return elem * 2;
});
console.log(doubleArrayElem);

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