Javascript polyfills are the javascript codes which are written to support unsupported javascript features.
This is javascript codes which are written to support few array methods(example: map, filter, forEach, reverse etc.) for those browsers which doesn't support these methods. Along with that anyone can learn how to create polyfill or custom array methods.
All array polyfills are written in index.js
file of main
branch of this repository.
Anyone have to add this file before of any js files or js codes of your application.
For example if anyone want to use in their application and if their root file of their application is index.html
if (!Array.prototype.map) {
Array.prototype.map = function(callback){
var arr = [];
try {
for(var i = 0; i<this.length; i++) {
arr.push(callback(this[i]));
}
}catch(e){
throw new Error(e);
}
return arr;
}
}
var arr = [1,2,3];
var newArr = arr.map((item) => item + 1);
console.log(newArr); // [2,3,4]
- This is same like array map method. This should work like below example:
var arr = [1,2,3];
var newArr = arr.map((item) => item + 1);
console.log(newArr); // [2,3,4]
console.log(arr === newArr) // false
- This is same like array filter method. This should work like below example:
var arr = [1,2,3];
var newArr = arr.filter((item) => item > 1);
console.log(newArr); // [2,3]
console.log(arr === newArr) // false
- This is same like array forEach method. This should work like below example:
var arr = [1,2,3];
var val = arr.forEach((item) => console.log(item));
// 1
// 2
// 3
console.log(val); // undefined
- This is same like array reverse method. This should work like below example:
var arr = [1,2,3];
var val = arr.reverse();
console.log(val) // [3,2,1]
console.log(val === arr) // true
- This is same like array reduce built-in method. This should work like below example:
var arr = [1,2,3];
var val = arr.reduce((prevVal, item) => { prevVal[item] = item - 1; return prevVal; }, {});
console.log(val) // {1: 0, 2: 1, 3: 2}