在JavaScript中检测404代码 [英] Detecting 404 code in JavaScript

问题描述

我需要能够在JavaScript中检测到丢失的图像。

I need to be able to detect a missing image in JavaScript.

由于href是由JavaScript计算的，因此无法使用服务器上的PHP。
文件存在时有效的脚本是：

PHP on the server can't be used because the href is computed by JavaScript. Script that works when the file exists is:

Data_ID = _DataRow.getDataItem()["Data_ID"];// Picks up the ID of the data
   _HitJPG = document.getElementById("HitJPG");
JPGFileName = _DataRow.getDataItem()["JPGFileName"];
directory = JPGFileName.slice(0, 10);
directory = directory.replace(/-/g, "/");

_HitJPG.innerHTML = "<a href=http://77.88.99.54/data/" + directory + "/" + JPGFileName + " ><h3>JPG File for this Data </h3>" + JPGFileName + "</a>";

在Div中设置InnerHTML之前，如何检测HTTP 404代码？

How can I detect a HTTP 404 code before I set the "InnerHTML" in the Div?

推荐答案

您可以使用 onload 和 onerror 检测是否可以加载图像的事件

You can use the onload and onerror events to detect wether or not the image can be loaded

var Data_ID     = _DataRow.getDataItem()["Data_ID"];
var _HitJPG     = document.getElementById("HitJPG");
var JPGFileName = _SETIDataRow.getDataItem()["JPGFileName"];//"2014-04-29T13-36-27.JPG"
var directory   = JPGFileName.slice(0, 10);

directory = directory.replace(/-/g, "/");

var image = new Image();

image.onerror = function() {
    // fail - image not available
}

image.onload = function() {
    // success - image available

    _HitJPG.innerHTML = "<a href=http://77.88.99.54/data/" + directory + "/" + JPGFileName + " ><h3>JPG File for this Data </h3>" + JPGFileName + "</a>";
}

image.src = "http://77.88.99.54/data/" + directory + "/" + JPGFileName

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