Javascript - 等待图像加载 [英] Javascript - wait images to be loaded

问题描述

var l = false;
var l2 = false;

var imm = new Image();
imm.src = "b.png";

imm.onload = function(){
l = true;
}

var imm2 = new Image();
imm2.src = "c.png";

imm2.onload = function(){
l2 = true;
}

如果<$ c $，我怎么能告诉这个javascript启动一个函数c> l 和 l2 是真的吗？我应该设置一个循环来不断检查这两个变量吗？有没有更有效的方法？我不希望我的脚本在没有图像的情况下启动但是使用 .onload 我可以等待只加载一个图像而不是所有图像。谢谢你的帮助！

How can I tell this javascript to start a function only if l and l2 are true? Should I set a loop which constantly check for these two variables? Is there any more efficient way? I don't want my script to start without images but with .onload I can wait for just one image to be loaded and not all of them. Thanks for your help!

推荐答案

无需循环。你可以让他们调用一个函数来检查l和l2是否为真并执行你想要做的事情：

No need for loops. You could let them call a function that checks if l and l2 are true and perform the thing you want to do:

var onLoaded = function() {
    if (l && l2) {
        // do your stuff
    }
}

imm.onload = function(){
    l = true;
    onLoaded(); // call to onLoaded
}

imm2.onload = function(){
    l2 = true;
    onLoaded(); // call to onLoaded
}

它基本上是一个简单的观察者模式。有一些jQuery插件，如 Radio.js ，可以为您封装。

It is basically a simpler form of the Observer Pattern. There are jQuery plugins such as Radio.js that encapsulate this for you.

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