ES5 Object.assign equivalent

Question

I wanted to do something which is very straight-forward using Object.assign.

var firstObj = {name : "Saba H.", rollNo : 1}; var secondObj = {college : "WCE"}; var wholeObj = Object.assign(firstObj, secondObj);  console.log(wholeObj); // {name : "Saba H.", rollNo : 1, college : "WCE"} 

As Object.assign is part of ECMAScript6 harmony proposal and not supported across many browsers, is it possible to do with ES5? If not then is there any micro library?

Answer 1

In underscore.js you can use like,

_.extend(firstObj, secondObj); 

In jQuery, you can use,

$.extend({},firstObj,secondObj); 

In pure javascipt, you can merge n number of objects by using this function:

function mergeObjects() {     var resObj = {};     for(var i=0; i < arguments.length; i += 1) {          var obj = arguments[i],              keys = Object.keys(obj);          for(var j=0; j < keys.length; j += 1) {              resObj[keys[j]] = obj[keys[j]];          }     }     return resObj; } 

Answer 2

I found a working polyfill for Object.assign on MDN (awesome, thanks!):

if (typeof Object.assign != 'function') {   // Must be writable: true, enumerable: false, configurable: true   Object.defineProperty(Object, "assign", {     value: function assign(target, varArgs) { // .length of function is 2       'use strict';       if (target == null) { // TypeError if undefined or null         throw new TypeError('Cannot convert undefined or null to object');       }        var to = Object(target);        for (var index = 1; index < arguments.length; index++) {         var nextSource = arguments[index];          if (nextSource != null) { // Skip over if undefined or null           for (var nextKey in nextSource) {             // Avoid bugs when hasOwnProperty is shadowed             if (Object.prototype.hasOwnProperty.call(nextSource, nextKey)) {               to[nextKey] = nextSource[nextKey];             }           }         }       }       return to;     },     writable: true,     configurable: true   }); }