How do I create an object from two array indexes?

I am trying to create a javascript object with two array indexes, but it does not seem possible. Why is that? For example:

var arr = ["name","john"];
var obj = {arr[0]:arr[1]}

>Solution :

Computed property names need brackets [myPropName]

var arr = ["name","john"]
var obj = {[arr[0]]:arr[1]}

obj.name // 'john'