Question

I need to built a object property out of strings
but how could I use the value of this string as property name?

var x = 'a';
var y = 'b';
var xy = x + y;

var z = {
    xy: 'some text'
};

Now I could access it via z['xy'] but not via z['ab'].

Answer 1

You’re trying to write

var z = {};
z[xy] = 'some text';

You cannot do this using an object literal.