使用JavaScript检查服务器上是否存在图像？ [英] Check if image exists on server using JavaScript?

问题描述

使用javascript有一种方法可以判断服务器上是否有资源可用？例如，我将图像1.jpg - 5.jpg加载到html页面中。我想每分钟调用一次JavaScript函数，大致会执行以下的临时代码...

Using javascript is there a way to tell if a resource is available on the server? For instance I have images 1.jpg - 5.jpg loaded into the html page. I'd like to call a JavaScript function every minute or so that would roughly do the following scratch code...

if "../imgs/6.jpg" exists:
    var nImg = document.createElement("img6");
    nImg.src = "../imgs/6.jpg";

想法？谢谢！

推荐答案

你可以使用类似的东西：

You could use something like:

function imageExists(image_url){

    var http = new XMLHttpRequest();

    http.open('HEAD', image_url, false);
    http.send();

    return http.status != 404;

}

显然你可以使用jQuery / similar来执行你的HTTP请求。

Obviously you could use jQuery/similar to perform your HTTP request.

$.get(image_url)
    .done(function() { 
        // Do something now you know the image exists.

    }).fail(function() { 
        // Image doesn't exist - do something else.

    })

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