object property name from another object value in javascript?

Question

ok, so, we have the option to do this:

var test ='name';

var obj[test] ='my name';

So this is actually:

var obj['name']='my name';

right?

Now for the question:

how do I do :

var test = 'name';

obj.test ='my name';

so that when I output obj.name it returns 'my name' ?