How do I set a variable to be a object's key so I can access an object dynamically in javascript?

Question

I want to use a variable to hold a key name for an object so I can do the below.

var obj = {name:'john', age: 8}
var holder 

holder can be name or age so obj.holder can return 'john' or 8 depending on what I set holder

How do I set a variable to be a object's key so I can access an object dynamically in javascript?

Answer 1

Just try with bracket notation when accessing the object properties:

var obj = {name:'john', age: 8}
var holder = 'name';

obj[holder]; // john

holder = 'age';
obj[holder]; // 8

Answer 2

var obj = {name:'john', age: 8};

var index = "john";
var holder = obj[index];