<div id="div1">

             <input type="file" id="uploadfile" style="width: 100px; height: 25px;" />

             <input id="b1" type="button" value="上传" style="display: inline-block; width: 40px; height: 25px;" />

             <img id="img1" src="" />

         </div>

 window.onload = function () {

     document.getElementById("uploadfile").addEventListener("change", function () {

         //1、获取所选的文件 暂时只选一个

         var filereader = new FileReader();

         filereader.onloadend = function (event) {

             console.log("a");

             var filedata = event.target.result;

             document.getElementById("img1").src = filedata;

         }

         var file = document.getElementById("uploadfile").files[0];

         filereader.readAsDataURL(file);

     }, true);

 }