Multiple conditions with yepnope

问题

I use yepnope.js as a resource loaded. I want to execute code in my JS module only when all the dependencies for that module have been loaded. I do not want to load JS dependencies that already been loaded.

Suppose, I have dependencies D1.js and D2.js. I tried

yepnope({
    load: ['D1.js', 'D2.js],
    complete: function() {
        //execute my code here
    }
});

That works, but, resources are loaded every time, even if they were already loaded before.

If I do multiple tests like that:

yepnope([{
    test: $().d1,
    nope: 'D1.js'
},
{
    test: $().d2,
    nope: 'D2.js'
}]);

It's not clear where to put the overall completed function -- the one that runs after all the resources have been loaded.

Is it possible to do this with yepnope, or do I need to use a different component?

Thanks.

回答1:

The callbacks are run after the corresponding scripts are executed (not just loaded). All the scripts run in order, so if you put a callback or a complete property on the last object, it'll run last.

回答2:

Let's say you need to conditionally load jquery.js, jquery.jgrowl.js, and jquery.powertip.js. You'd expect the following code to work:

yepnope([{
  test: typeof(window.jQuery) === 'undefined' || 
        jQuery.fn.jquery.match(/^1\.[0-9]+/) < 1.7,
  yep: '//cdnjs.cloudflare.com/ajax/libs/jquery/2.0.0/jquery.min.js'
},
{
  test: typeof(window.jQuery) === 'undefined' 
        || typeof(window.jQuery.fn.jGrowl) === 'undefined',
  yep: ['//cdnjs.cloudflare.com/ajax/libs/jquery-jgrowl/1.2.12/jquery.jgrowl.min.js',
        '//cdnjs.cloudflare.com/ajax/libs/jquery-jgrowl/1.2.12/jquery.jgrowl.css'],
  complete: function() {
    console.log('completed loading jGrowl (should fire first, or not at all)');
  }
},
{
  test: typeof(window.jQuery) === 'undefined' 
        || typeof(window.jQuery.fn.powerTip) === 'undefined',
  yep: ['//cdnjs.cloudflare.com/ajax/libs/jquery-powertip/1.1.0/jquery.powertip.js', 
        '//cdnjs.cloudflare.com/ajax/libs/jquery-powertip/1.1.0/jquery.powertip.min.css'],
  complete: function() {
    console.log('completed loading powertip'); 
    jQuery.jGrowl("Growling!");
  }
}
]);

However, if this runs on a page where jquery.powertip.js is already loaded, but jquery.jgrow.js is not, this will throw an error, due to the 'complete' callback being fired right away, instead of when all the files are done loading.

The following fiddle demonstrates this bug with yepnope 1.5.4: http://jsfiddle.net/dergachev/HHxK2/

Note also that in the current trunk (master branch) of yepnope, this bug goes away. It's probably related to the following tickets (which were never backported to 1.5.4):

https://github.com/SlexAxton/yepnope.js/pull/140
https://github.com/SlexAxton/yepnope.js/issues/132
https://github.com/SlexAxton/yepnope.js/issues/100
https://github.com/SlexAxton/yepnope.js/issues/96
https://github.com/SlexAxton/yepnope.js/issues/29

来源：https://stackoverflow.com/questions/12330130/multiple-conditions-with-yepnope

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