namespace

README.md

namespace

//"window" //"window.a" //"a" //"a.b.c" //any custom context

index.js

function (a,b,c,d){c=a.replace(/^window.?/,"").split("."),b=b||window;while(d=c.shift())b=b[d]=b[d]||{};return b}

namespace.js

function(
    a, 	//input string
    b, 	//context
    c, 	//(placeholder)
    d 	//(placeholder)
){
    c = a.replace(/^window.?/, '').split('.');	//replace ^window and split
    b = b || window;	                        //default context
    while(d = c.shift()) b = b[d] = b[d] || {};
    return b;
}

package.json

{
  "name": "namespace",

  "description": "namespace",

  "keywords": [
    "namespace",
    "javascript",
    "斯人",
    "leecade"
  ]
}

How about using the replace for the loop?

function (a,b){b=b||window;a.replace(/^window\.|([^\.]+)/g,function(c,d){b=d?b[d]||{}:b});return b}