javascript 如何检查图像是否已缓存在 js 中？
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how to check if an image was cached in js?
提问by looping
when I joined an interview , I was asked the question, I didn't know how to answer it .
我参加面试的时候被问到这个问题，我不知道怎么回答。
do you know the key point of the question?
你知道问题的关键点吗？
回答by Blender
Check if the completeattribute of the Imageobject is true:
检查对象的complete属性Image是否为true：
function is_cached(src) {
var image = new Image();
image.src = src;
return image.complete;
}
It seems to work (although it'll load the image if it isn't in the cache, which might not be what you want):
它似乎有效（尽管它会加载不在缓存中的图像，这可能不是您想要的）：
> 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
回答by Sudhir Bastakoti
you could check like:
你可以像这样检查：
function is_cached(img_url){
var imgEle = document.createElement("img");
imgEle.src = img_url;
return imgEle.complete || (imgEle.width+imgEle.height) > 0;
}
//and check, returns true or false depending on cached or not
is_cached("http://www.somesite.com/some_image.jpg");
