图片预加载回调射击所有图像都加载之前

Question

问题：

我试图做的图像预加载，发现this awesome solution我试图adapt.I了代码，并包裹在一个函数返回一个承诺，但我注意到done()处理程序被称为之前所有的图像被加载，我做错了什么？

代码：

function preload(args) { 

    var $defer = $.Deferred(); 
    var preload = args; 
    var promises = []; 
    for (var i = 0; i < preload.length; i++) { 
    (function(url, promise) { 
     var img = new Image(); 
     img.onload = function() { 
     promise.resolve(); 
     console.log("loaded:" + url); 
     }; 
     console.log("loading:" + url); 
     img.src = url; 
    })(preload[i], promises[i] = $.Deferred()); 
    } 
    $.when.apply($, promises).done(function() { 
    console.log("All images ready sir!"); 
    $defer.resolve(); 
    }); 

    return $defer; 
} 

var images = ['https://pbs.twimg.com/media/CbM1w65UcAAKfSJ.jpg', 'https://www.kenrockwell.com/nikon/d600/sample-images/600_0985.JPG', 'https://developer.nvidia.com/sites/default/files/akamai/gameworks/blog/GameWorks_Vulkan_and_OpenGL_Samples/vulkan2.png', 'https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcSKJ1fJHxLQ6unFkHZnHJoT-RfqrBvWMrzhmRFAPUt0VvdvZSDd', 'https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcTyvamruO8NCTeQJXtQaXM8xEQS5P9ANh_npfgZpv-7x8ISvzX5zg']; 

preload(images).done(function() { 
    console.log("OK, begin business process.."); 

}); 

控制台输出：

的jsfiddle：

https://jsfiddle.net/sajjansarkar/f5k94n2r/

Answer 1

交换这两行

promise.resolve(); 
    console.log("loaded:" + url); 

许是解决触发决心链的其余部分。然后添加日志消息。