如何使用JavaScript检查图像URL为404 [英] How to check image url is 404 using javascript

问题描述

用例:

1. 当src不为null且alt标签不为null时，则显示src的图像.
2. 然后检查src图片网址不是404.
3. 当src为null且alt不为null时，名字的显示图像.
4. 当src和alt为null时，则显示默认图片

HTML:

<img class="imagelazy" id="lazyimage" src="http://url" alt="ankit">

Javascript:

function imagelazy() {

    $(document).ready(function()

        {
            var image = $(".imagelazy").attr('src');
            var altdata = $(".imagelazy").attr('alt');
            var alt = $(".imagelazy").attr('alt').split("");
            //var imagepath="http://im.gifbt.com/userimages/"+alt[0].toLowerCase()+".jpg";
            var defaultimage = "http://im.gifbt.com/img/no-pic.jpg";
            console.log(image);
            console.log(alt);
            $(".imagelazy img")
                .error(function() {
                    $(this).hide();
                })
                .attr("src", defaultimage);

            if (image != '' && altdata != '') {
                console.log("afeef");
                $('.imagelazy').bind('error', function() {
                    $(this).attr("src", defaultimage);
                });
                $(".imagelazy img")
                    .error(function() {
                        $(this).hide();
                    })
                    .attr("src", defaultimage);


            } else if (image == '' && altdata != '') {
                $.each($('.imagelazy'), function(index, value) {
                    var alt1 = $(this).attr('alt').split("");
                    console.log(alt1);
                    if (alt1 != '') {
                        var imagepath1 = "http://im.gifbt.com/userimages/" + alt1[0].toLowerCase() + ".jpg";
                    }
                    console.log(this.outerHTML);
                    console.log(imagepath1);
                    $(this).attr("src", imagepath1);
                });


            } else if (altdata == '' && image == '') {
                $.each($('.imagelazy'), function(index, value) {
                    $(this).attr("src", defaultimage);
                    console.log(this.outerHTML);
                });
            }

        });
}

问题

• 向下滚动页面时脚本不起作用.
• 在src中设置图像并设置alt标签后，还会显示名字图像.
• onerror在js中不起作用.
• 我在Google上搜索了很多内容，没有找到解决此问题的方法.
• 我发现了lazy.min.js js，它设置了src ="和data-src ="pathimage" 将解决此问题.

• 我们的要求是优化html，这就是为什么我通过js搜索替代解决方案的原因.

• Script is not working when scrolling down the page.
• When the image is set in src and alt tag is set then also first name image is displayed.
• onerror is not working in js.
• i have googled a lot coudln"t found the solution for this issue.
• i have found lazy.min.js js which set src="" and data-src="pathimage" would handled this issue.

• our requirement is optimize html that why im searching for alternate solution through js.

我找到了jquery链接: https://api.jquery.com/error/

i have found jquery link : https://api.jquery.com/error/

推荐答案

jQuery Ajax:

jQuery Ajax:

$.ajax({
    url:'http://www.example.com/somefile.ext',
    type:'HEAD',
    error: function()
    {
        //file not exists
    },
    success: function()
    {
        //file exists
    }
});

JavaScript:

Javascript:

function UrlExists(url)
{
    var http = new XMLHttpRequest();
    http.open('HEAD', url, false);
    http.send();
    return http.status!=404;
}

图像检查:

function ImageExist(url) 
{
   var img = new Image();
   img.src = url;
   return img.height != 0;
}

其他:

$.get(url)
    .done(function() { 
        // exists code 
    }).fail(function() { 
        // not exists code
    })

HTML:

<img src="image.gif" onerror="imgError()" />

function imgError()
{
alert('The image could not be loaded.');
}

这篇关于如何使用JavaScript检查图像URL为404的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！