Javascript 图像对象 - 处理 onload 事件
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Javascript Image Object - Handle onload Event
提问by user398341
I'm trying to preload image on click event:
我正在尝试在点击事件上预加载图像：
// new image object
var imgObject = new Image();
// assign the path to the image to the src property
imgObject.src = document.URL + 'image/image.jpg';
// check if image has loaded
if (imgObject.complete) {
But the complete call never returns true on the first click - any idea what I'm missing here?
但是，在第一次点击时，完整的调用永远不会返回 true - 知道我在这里遗漏了什么吗？
回答by James Hill
.completeis a property of the image object, not an event that you can attach to. Use the onloadevent:
.complete是图像对象的属性，而不是您可以附加到的事件。使用onload事件：
var image = new Image();
image.onload = function() {
alert('image loaded');
};
image.src = document.URL + 'image/image.jpg';
Note:Be sure to attach to the onload hander before setting the source attribute.
注意：在设置 source 属性之前，一定要附加到 onload 处理程序。
Note Explanation: Image caching. If the image is cached then the onload event will fire immediately (sometimes before setting the handler)
注释说明：图像缓存。如果图像被缓存，则 onload 事件将立即触发（有时在设置处理程序之前）
