function CheckFiles(obj) {
var array = new Array('gif', 'jpeg', 'png', 'jpg'); //可以上傳的文件類型
if (obj.value == '') {
alert("讓選擇要上傳的圖片!");
return false;
}
else {
var fileContentType = obj.value.match(/^(.*)(\.)(.{1,8})$/)[3]; //這個(gè)文件類型正則很有用：）
var isExists = false;
//$("#img").attr("src", obj.value)
var fileInput = $("#logo")[0];
byteSize = fileInput.files[0].size;
//var size = Math.ceil(byteSize / 1024);/*用來判斷圖片大小的*/
//var tWidthHeight = testWidthHeight(fileInput);
for (var i in array) {
if (fileContentType.toLowerCase() == array[i].toLowerCase()) {
isExists = true;
}
}
if (isExists == false) {
obj.value = null;
//alert("上傳圖片類型不正確!");
$("#tishi").text("上傳圖片類型不正確");
$("#tishi").css("color", "red");
return false;
}
/*判斷圖片的大小是否合格*/
testWidthHeight(fileInput, obj);
}
}

function testWidthHeight(file, obj) {
var isAllow = false;
var Max_Width = "291";
var Max_Height = "77";
if (file.files && file.files[0]) {
var fileData = file.files[0];

//讀取圖片數(shù)據(jù)
var reader = new FileReader();

reader.onload = function (e) {
var data = e.target.result;
//加載圖片獲取圖片真實(shí)寬度和高度
var image = new Image();
image.onload = function () {
var width = image.width;
var height = image.height;
isAllow = width >= Max_Width && height >= Max_Height;
pd(isAllow, obj, fileData);
};
image.src = data;
};
reader.readAsDataURL(fileData);

} else {
//IE下使用濾鏡來處理圖片尺寸控制
//文件name中IE下是完整的圖片本地路徑
var input = $("#logo")[0];
//var input = uploader.get('target').all('input').getDOMNode();
input.select();
//確保IE9下，不會(huì)出現(xiàn)因?yàn)榘踩珕栴}導(dǎo)致無法訪問
input.blur();
var src = document.selection.createRange().text;
var img = $('<img style="filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=image);width:300px;visibility:hidden;" />').appendTo('body').getDOMNode();
img.filters.item('DXImageTransform.Microsoft.AlphaImageLoader').src = src;
var width = img.offsetWidth;
var height = img.offsetHeight;
$(img).remove();
isAllow = width >= Max_Width && height >= Max_Height;
pd(isAllow, obj, fileData);
}

}
function pd(o, obj, fileData) {
if (o) {
obj.value = null;
$("#tishi").text("圖片超過限定大小上傳失敗");
$("#tishi").css("color", "red");
$("#ImgPr").attr('src', '');
} else {
console.log("0000");
$("#tishi").text("上傳成功");
$("#tishi").css("color", "green");
$("#ImgPr").attr('src', geturl(fileData))
}
}

function geturl(file) {
var url = null;
if (window.createObjectURL != undefined) {
url = window.createObjectURL(file)
} else if (window.URL != undefined) {
url = window.URL.createObjectURL(file)
} else if (window.webkitURL != undefined) {
url = window.webkitURL.createObjectURL(file)
}
return url
}

html 部分

<asp:FileUpload ID="logo" runat="server" Style="width: 50%" onchange="CheckFiles(this);" />
<label >&nbsp;logo尺寸大小（291px*77px）</label>
<label id="tishi"></label>

<div><img id="ImgPr" width="120" height="120" /></div>