Question

can anyone explain how this below works?

var MYAPP = {};
MYAPP.namespace = function(name){
    var parts = name.split('.');
    var current = MYAPP;
    for (var i in parts) {
        if (!current[parts[i]]) {
            current[parts[i]] = {};
        }
        // shouldn't this line override the MYAPP object with all it's properties?
        current = current[parts[i]];
    }
}

Answer 1

current is first assigned a reference to MYAPP, after that, within the loop, for every part of the Array from name.split it is subsequently assigned a reference to the freshly made property of MYAPP. So nothing is overwritten, because it’s all references.

in words for example if you execute MYAPP.namespace(foo.bar) this happens:

• first: current points to MYAPP
• now go into the loop. If current /*is ref to MYAPP*/ .foo doesn’t exist, create MYAPP.foo
• let current point to MYAPP.foo
• if current /*is now ref to MYAPP.foo*/ .bar doesn’t exist create it
• finally MYAPP contains:
  • MYAPP.foo
  • MYAPP.foo.bar
• If you wanted to assign the same to MYAPP as MYAPP.namespace(foo.bar) using an object literal, you would write
  • var MYAPP = { foo: { bar: {} }