javascript上传图片前预览图片兼容大多数浏览器
<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
代码如下:
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