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  • 【案例】图片上传

    <!DOCTYPE html>

    <html lang="en">

    <head>

            <meta charset="UTF-8">

            <title>文件上传</title>

            <style>

                     #box{

                             400px;

                             height: 400px;

                             border: 1px solid #ccc;

                             margin: 20px 20px;

                     }

            </style>

    </head>

    <body>

            <input type="file">

            <div id = "box"></div>

            <span>图片上传进度:</span>

            <progress min="0" max="0" value="0"></progress>

    </body>

    <script>

            //获取元素

            var input = document.getElementsByTagName('input')[0];

            var box = document.getElementById('box');

            var progress = document.getElementsByTagName('progress')[0];

            input.onchange = function(e){

                     var e = window.event || e;

                     /**

                             首先使用input读取这个文件,然后使用文件读取对象得到文件路径,再将文件路径赋值给img标签。

                     **/

                     //读取文件信息

                     var file = e.target.files[0];

                     //实例化文件读取对象;FileReader()是JS自身的对象

                     var reader = new FileReader();

                     //读取file文件的URL信息

                     reader.readAsDataURL(file);

                     reader.onload = function(){

                             //创建一个img对象

                             var img = document.createElement('img');

                             img.src = this.result;

                             img.style.width = '400px';

                             img.style.height = '400px';

                             box.appendChild(img);

                     }

                     //文件读取进度条

                     reader.onprogress = function(ent){

                             //ent.loaded是当前进度    ent.total是总体进度

                             progress.value = ent.loaded / ent.total;

                     }

            }

    </script>

    </html>

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  • 原文地址:https://www.cnblogs.com/sherryStudy/p/img_load.html
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