Initializing a namespace tree [closed]

$.extend(true,window.namespace,{util:{}});

No need to drag in jQuery for this. $.extend(true, window.namespace, {util:{}}) might help you merge objects. But in the end, you're still manually building the namespace tree.

Making this worse is the fact that you're deep-copying. Deep copy duplicates everything but a few data types. IIRC, functions, regexes and dates aren't cloned. Primitives, objects and arrays are recreated. This is bad for memory.

window.namespace.util.myutility = new (function(){
  return {};  
})

This... is wrong. When you use a constructor, you don't return anything from it. Otherwise, you create an instance of the constructor, but never get that instance in the end, just the value you returned. This is no different than just doing window.namespace.util.myutility = {} minus the fact that things can hide from the closure.

window.namespace = window.namespace || {}; 
window.namespace.utils || (window.namespace.utils = {});

The problem with this approach is you're doing manually what you could have done automatically. Computers are built to do repetitive tasks for you. Why not automate the process of nesting objects? Here's one piece of code from my adventures which used it to create namespaces:

// Given a dot-separated string, it creates a hierarchy on a provided object
// or globally, and returns the last object in the name space.

function useNamespace(namespace, rootObject){
  return namespace.split('.').reduce(function(parent, child){
    // If parent isn't an object (maybe some kind of already-defined property holding a primitive), throw.
    if(!parent || typeof parent !== 'object') throw Error ('Namespace encountered a primitive');
    // Otherwise, return existing child or assign a new object as child.
    return parent[child] = parent[child] || {};
  }, rootObject || window);
}

// Adding window.foo.bar
var bar = useNamespace('foo.bar');
bar.hello = "world";

// Extending bar with boom (window.foo.baz.boom)
var boom = useNamespace('foo.baz.boom');
boom.beach = "get it now!";

// Extend boom directly (window.foo.baz.boom.topher)
var chris = useNamespace('topher', boom);
chris.lion = "tiger";

// They should live under the same object
document.write(JSON.stringify(foo));