Equivalent of Underscore _.pluck in pure JavaScript
In ES5:
function pluck(array, key) { return array.map(function(obj) { return obj[key]; });}In ES6:
function pluck(array, key) { return array.map(o => o[key]);}
You can do it with the native JavaScript .map():
Array.prototype.pluck = function(key) { return this.map(function(object) { return object[key]; });};edit — modifying built-in prototype objects should be done with care; a better way to add the function (should you be OK with the idea of doing so in general) would be with Object.defineProperty so that it can be made non-enumerable:
Object.defineProperty(Array.prototype, "pluck", { value: function(key) { return this.map(function(object) { return object[key]; }); }});
You are so close. You need to change:
newArr.push(arr[i].key);to:
newArr.push(arr[i][key]);Consider this:
var obj = { myKey: 'my Value', theKey: 'another value' };var theKey = 'myKey';alert(obj.theKey); // another valuealert(obj[theKey]); // my Value// You can also send in strings here:alert(obj['theKey']); // another valueHope you get my point.