JS实现未上传图片预览
function
checkType(upload){
var
image = document.getElementById(upload).value;
var
extStart = image.lastIndexOf(
"."
);
var
ext = image.substring(extStart, image.length).toUpperCase();
if
( ext !=
".PNG"
&& ext !=
".GIF"
&& ext !=
".JPG"
&& ext !=
".JPEG"
) {
alert(
"图片限于png，gif，jpeg，jpg格式！"
);
return
false
;
}
return
true
;
}
function
setImagePreview(upload,preview) {
if
(checkType(upload)){
showTips(
'result'
,
'图片预览：'
,0);
var
docObj=document.getElementById(upload);
var
imgObjPreview=document.getElementById(preview);
if
(docObj.files && docObj.files[0]){
//火狐下，直接设img属性
imgObjPreview.style.width =
'160px'
;
imgObjPreview.style.height =
'120px'
;
try
{
imgObjPreview.src = docObj.files[0].getAsDataURL();
}
catch
(e){
//火狐7以上版本不能用上面的getAsDataURL()方式获取，需要一下方式
imgObjPreview.src = window.URL.createObjectURL(docObj.files[0]);
}
}
else
{
//IE下，使用滤镜
docObj.select();
var
imgSrc = document.selection.createRange().text;
var
localImagId = document.getElementById(
"localImag"
);
//必须设置初始大小
localImagId.style.width =
"160px"
;
localImagId.style.height =
"120px"
;
//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 =
'block'
;
document.selection.empty();
}
return
true
;
}
}
摘自：http://www.oschina.net/code/snippet_187608_34433