gistfile1.js

/*
  How to make a domReady function
*/
;(function(win){

  var doc = win.document
      /* 
        We'll use the document.readyState string
        to define weather or not the dom is ready. 
        The RegExp matches all the states we can 
        act on.  
      */
    , readyStateRegExp = /interactive|loaded|complete/
      /*
        We need to store the callbacks that are
        waiting for the document to be ready here. 
      */
    , domReadyStack = []
      /*
        Just a boolean not to repeat the test once
        we've tested a positive state. 
      */
    , isReady = false
  
  /*
    This method checks the document.readyState
    string, and calls itself recursively as long
    as necessary every 10ms. 
  */
  function checkReadyState(){
    var item
    if(readyStateRegExp.test(doc.readyState)) {
      isReady = true
      while(item = domReadyStack.shift()) {
        /*
          The main reason why to use setTimeout here
          is that if an error is thrown within the
          callback, we don't wan't the whole stack
          to be stopped because the error has gained
          the current 
        */
        setTimeout(item, 0)
      }
      /*
        Early return there, not to call the method 
        again. 
      */
      return
    }
    setTimeout(checkReadyState, 10)
  }

  setTimeout(checkReadyState, 10)

  function domReady(fn){
    if(typeof fn != "function") {
      return
    }
    if(isReady) {
      setTimeout(fn, 0)
      return
    }
    domReadyStack.push(fn)
  }

  win.domReady = domReady

})(this.window)