文件上传预览

<fieldset><legend>使用readAsDataUrl()方法预览图片</legend><input type="file" name="fileUpload" id="fileUpload" onchange="filePrevImg(this.files);" multiple="true" /><ul id="prevUpload"></ul> </fieldset>
<script>
function $$(id){return document.getElementById(id);}function filePrevImg(files){//检测浏览器是否支持FileReader对象if(typeof FileReader == "undefined"){alert("您的浏览器不支持FileReader对象！");}var strHtml = "";for(var intI=0;intI<files.length;intI++){var tmpFile = files[intI];var reader = new FileReader();//每循环一次都要重新new一个FileReader实例
                    reader.readAsDataURL(tmpFile);reader.onload=function(e){alert(e.target.result);strHtml += "<span>";strHtml += "<img src='"+e.target.result+"' alt=''/>";strHtml += "</span>";$$("prevUpload").innerHTML = "<li>"+strHtml+"</li>";};}}</script>