js实现图片上传并正常显示

项目经常会用到头像上传，那么怎么实现呢？

首先是HTML布局：

<label for="thumbnail">缩略图</label> <div> <input type="file"> </div>

jquery方式，IE不支持，但IE会获得绝对的上传路径信息：

function getObjectURL(file) { var url = null ; if (window.createObjectURL!=undefined) { // basic url = window.createObjectURL(file) ; } else if (window.URL!=undefined) { // mozilla(firefox) url = window.URL.createObjectURL(file) ; } else if (window.webkitURL!=undefined) { // webkit or chrome url = window.webkitURL.createObjectURL(file) ; } return url ; } $('#thumbnail').change(function() { var eImg = $('<img />'); eImg.attr('src', getObjectURL($(this)[0].files[0])); // 或 this.files[0] this->input $(this).after(eImg);});

网上找一份可用的代码非常不易，经过不断的筛选总结才得出兼容所有的文件上传显示
HTML布局

<form action='' method='post'> <input type='file' onchange='show()' value='' /> <img src='https://www.jb51.net/article/1.jpg' alt='' /> </form>

JS代码：

<script type="text/javascript"> function getPath(obj,fileQuery,transImg) { var imgSrc = '', imgArr = [], strSrc = '' ; if(window.navigator.userAgent.indexOf("MSIE")>=1){ // IE浏览器判断 if(obj.select){ obj.select(); var path=document.selection.createRange().text; alert(path) ; obj.removeAttribute("src"); imgSrc = fileQuery.value ; imgArr = imgSrc.split('.') ; strSrc = imgArr[imgArr.length - 1].toLowerCase() ; if(strSrc.localeCompare('jpg') === 0 || strSrc.localeCompare('jpeg') === 0 || strSrc.localeCompare('gif') === 0 || strSrc.localeCompare('png') === 0){ obj.setAttribute("src",transImg); obj.style.filter= "progid:DXImageTransform.Microsoft.AlphaImageLoader(src='"+path+"', sizingMethod='scale');"; // IE通过滤镜的方式实现图片显示 }else{ //try{ throw new Error('File type Error! please image file upload..'); //}catch(e){ // alert('name: ' + e.name + 'message: ' + e.message) ; //} } }else{ // alert(fileQuery.value) ; imgSrc = fileQuery.value ; imgArr = imgSrc.split('.') ; strSrc = imgArr[imgArr.length - 1].toLowerCase() ; if(strSrc.localeCompare('jpg') === 0 || strSrc.localeCompare('jpeg') === 0 || strSrc.localeCompare('gif') === 0 || strSrc.localeCompare('png') === 0){ obj.src = fileQuery.value ; }else{ //try{ throw new Error('File type Error! please image file upload..') ; //}catch(e){ // alert('name: ' + e.name + 'message: ' + e.message) ; //} } } } else{ var file =fileQuery.files[0]; var reader = new FileReader(); reader.onload = function(e){ imgSrc = fileQuery.value ; imgArr = imgSrc.split('.') ; strSrc = imgArr[imgArr.length - 1].toLowerCase() ; if(strSrc.localeCompare('jpg') === 0 || strSrc.localeCompare('jpeg') === 0 || strSrc.localeCompare('gif') === 0 || strSrc.localeCompare('png') === 0){ obj.setAttribute("src", e.target.result) ; }else{ //try{ throw new Error('File type Error! please image file upload..') ; //}catch(e){ // alert('name: ' + e.name + 'message: ' + e.message) ; //} } // alert(e.target.result); } reader.readAsDataURL(file); } } function show(){ //以下即为完整客户端路径 var file_img=document.getElementById("img"), iptfileupload = document.getElementById('iptfileupload') ; getPath(file_img,iptfileupload,file_img) ; } </script>