如何检查图像是否缓存在js中？ [英] how to check if an image was cached in js?

问题描述

当我参加面试时，我被问到这个问题，我不知道如何回答。

when I joined an interview , I was asked the question, I didn't know how to answer it .

你知道这个问题的关键点吗？

do you know the key point of the question?

推荐答案

检查 完成属性>图像对象是 true ：

function is_cached(src) {
    var image = new Image();
    image.src = src;

    return image.complete;
}

它似乎有用（虽然它会加载图像，如果它不是' t在缓存中，可能不是你想要的）：

It seems to work (although it'll load the image if it isn't in the cache, which might not be what you want):

> is_cached('http://cdn.sstatic.net/stackoverflow/img/sprites.png?v=3')
false
> is_cached('http://cdn.sstatic.net/stackoverflow/img/sprites.png?v=3')
true

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