Question

我正在使用此代码预加载图片并稍后通过id引用它们。它适用于大多数浏览器和ipad，但IE8会产生此错误：

'无法获取未定义的空引用'

的属性'target'

这是我的代码：

var images = [{id:"kids", url:"assets/driekids.png"}, {id:"title",url:"assets/gametitle.png"}];
var assets = [];
var fnCallback = fn;
var loaded = 0;

this.startLoading = function() {
    var t = this;
    for(var i = 0;i<images.length;i++){
        var r = new Image();
        r.src = images[i].url;
        r.name = images[i].id;
        r.onload = function(){t.checkLoaded();};
    }
}

this.checkLoaded = function(e) {    
    this.assets[e.target.name] = e.target;  
    loaded++;
    if(loaded == images.length) fnCallback();       
}

我的问题：这种图像预加载方式是否可以在IE8上使用新的Image（）？

Answer 1

在IE中，您可以获得如下事件对象：

window.event

因此您必须对代码进行修改：

this.startLoading = function() {
    var t = this;
    for(var i = 0;i<images.length;i++){
        var r = new Image();
        r.src = images[i].url;
        r.name = images[i].id;
        r.onload = t.checkLoaded; // you dont want an anonymous function here
    }
}

this.checkLoaded = function(e) {
    // get the event object for both IE and other browsers
    var event = e || window.event;
    var target = e.target || event.srcElement ;
    this.assets[target.name] = target;  
    loaded++;
    if(loaded == images.length) fnCallback();       
}

在IE8中预加载图像时出错

1 个答案: