How to create an object property from a variable value in JavaScript? [duplicate]

Question

I want to add a new property to 'myObj', name it 'string1' and give it a value of 'string2', but when I do it it returns 'undefined:

var myObj = new Object; var a = 'string1'; var b = 'string2'; myObj.a = b;  alert(myObj.string1); //Returns 'undefined' alert(myObj.a); //Returns 'string2' 

In other words: How do I create an object property and give it the name stored in the variable, but not the name of the variable itself?

Answer 1

There's the dot notation and the bracket notation

myObj[a] = b; 

Answer 2

ES6 introduces computed property names, which allow you to do

var myObj = {[a]: b}; 

Note browser support is currently negligible.