javascript上传图片前预览图片兼容大多数浏览器

<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>