javascript 上传图片前预览图片

来源：互联网发布：c strchr(const 源码编辑：程序博客网时间：2024/05/23 19:13

<div id="localImag"><img  id="preview" width="-1" height="-1" style="display:none" /></div><asp:FileUpload ID="file_head" runat="server"  onchange="javascript:setImagePreview();" />

<script type="text/javascript">    function setImagePreview() {        var docObj = document.getElementById("ctl00_ContentMain_file_head");        var fileName = docObj.value;        if (!fileName.match(/.jpg|.gif|.png|.bmp/i)) {            alert('您上传的图片格式不正确，请重新选择！');            return false;        }        var imgObjPreview = document.getElementById("preview");        if (docObj.files && docObj.files[0]) {            //火狐下，直接设img属性            imgObjPreview.style.display = 'block';            imgObjPreview.style.width = '63px';            imgObjPreview.style.height = '63px';            //imgObjPreview.src = docObj.files[0].getAsDataURL();            if (window.navigator.userAgent.indexOf("Chrome") >= 1 || window.navigator.userAgent.indexOf("Safari") >= 1) {                imgObjPreview.src = window.webkitURL.createObjectURL(docObj.files[0]);            }            else {                imgObjPreview.src = window.URL.createObjectURL(docObj.files[0]);            }        } else {            //IE下，使用滤镜            docObj.select();            docObj.blur();            var imgSrc = document.selection.createRange().text;            var localImagId = document.getElementById("localImag");            //必须设置初始大小            localImagId.style.width = "63px";            localImagId.style.height = "63px";             //图片异常的捕捉，防止用户修改后缀来伪造图片            try {                                localImagId.style.filter = "progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale)";                localImagId.filters.item("DXImageTransform.Microsoft.AlphaImageLoader").src = imgSrc;            } catch (e) {                alert("您上传的图片格式不正确，请重新选择！");                return false;            }            imgObjPreview.style.display = 'none';            document.selection.empty();        }        return true;    }</script>

此js解决360浏览器显示图片问题。因为360浏览器6.2用的是Chrome的内核，而

window.URL.createObjectURL(docObj.files[0]);

只有在火狐下才认得到，chrome中不认识window.URL.createObjectURL，所有用Safari的window.webkitURL.createObjectURL