动态加载脚本时构造javascript和延迟执行

Question

I'm loading my javascript files using Modernizr.load() . Now lets say each page needs to call their own init method after everything has finished loading. But I put the loading in a template master, which is unaware of the child pages. How can the pages know when the dependencies have finished loading?

script

Page1Stuff= {
   init: function(){ alert('page 1 executed'); }
}
Page2Stuff= {
   init: function(){ alert('page 2 executed'); }
}

site master template

//Modernizr loads the script.
Modernizr.load([{
    load: 'jquery.js',
},
{
    load: 'script.js'
}]);

page1

$(function() {
    Page1Stuff.init();
});

page2

$(function() {
    Page2Stuff.init();
});

I think I see 2 problems here. If modernizr is still loading jquery, $ may not be defined. Also, Page2Stuff or Page1Stuff may not be defined.

Answer 1

In your template: Use the modernizer "complete" call back to emit a custom event to signal the loading is complete, also set a global variable saying that the scripts have been loaded.

In your page scripts: first check the global variable to see if all scripts have been loaded, if not, register a handler to listen for the custom event you emit when the loading completes.

In your template code:

// A simple object that calls its listeners when modernizer script loading completes.
global_scriptLoadingMonitor = (function() {
   var listeners = [];
   var isComplete = false;
   return {
      "addListener": function (listener) {
         listeners[listeners.length] = listener;
      },
      "complete": function () {
         isComplete = true;
         for (var i = listeners.length - 1; i >= 0; i--) {
            listeners[i]();
         }
      },
      "isComplete": isComplete
   }
})();

Modernizr.load([{
    load: 'jquery.js',
},
{
    load: 'script.js'
    complete: function () {
    {
       global_scriptLoadingMonitor.complete();
    }
}]);

Now in your Page1 do this:

if (global_scriptLoadingMonitor.isComplete) {
    $(function() {
        Page1Stuff.init();
    });
} else {
    global_scriptLoadingMonitor.addListener(function() {
        $(function() {
           Page1Stuff.init();
        });
    });
}

And similarly for page2.