javascript 从javascript重置文件上传控制
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Reset fileupload control from javascript
提问by IT researcher
I have a ASP website page where i have a upload control added
我有一个 ASP 网站页面，我在其中添加了一个上传控件
<asp:FileUpload ID="FileUpload1" runat="server"
BorderStyle="None" Width="215px" onchange="return checkfile();" style="margin-left: 14px" BackColor="#F0F0F0" />
From javascripti am validating the file which will be uploaded. If it is of type .exethen I will not allow to upload and give a message. if not i will display the file name in label "lblFileName" . But the problem if error(in case file is exe) then i want to reset the upload control(FileUpload1) . Now it will show only message but allows form to submit along with the .exefile.So how I can reset it?
从javascript我正在确认将要上传的文件。如果它是类型，.exe那么我将不允许上传和发送消息。如果不是，我将在标签“ lblFileName”中显示文件名。但问题是如果错误（如果文件是 exe），那么我想重置上传控件（FileUpload1）。现在它将只显示消息但允许表单与文件一起提交。.exe那么我如何重置它？
function checkfile() {
var filename = document.getElementById("FileUpload1").value;
var lastIndex = filename.lastIndexOf("\");
if (lastIndex >= 0) {
filename = filename.substring(lastIndex + 1);
}
var FileExt = filename.split('.').pop();
if (FileExt == "exe") {
document.getElementById('<%=lblFileName.ClientID%>').innerHTML = "you cannot attach exe file";
return false;
}
else {
document.getElementById('<%=lblFileName.ClientID%>').innerHTML = filename;
}
}
回答by Just code
Your code is the problem onchange="return checkfile();"
你的代码是问题 onchange="return checkfile();"
And your function should look like
你的功能应该看起来像
function checkfile() {
var filename = document.getElementById("FileUpload1").value;
var lastIndex = filename.lastIndexOf("\");
if (lastIndex >= 0) {
filename = filename.substring(lastIndex + 1);
}
var FileExt = filename.split('.').pop();
if (FileExt == "exe") {
document.getElementById('lblFileName').innerHTML = "you cannot attach exe file";
document.getElementById("FileUpload1").value='';
return false;
}
else {
document.getElementById('lblFileName').innerHTML = filename;
}
}
Return will disallow file to put in your file upload control so this will solve your problem
Return 将不允许文件放入您的文件上传控件中，因此这将解决您的问题
Please check demohere
请在此处查看演示
回答by Besnik Kastrati
I am doing it this way using jquery:
我正在使用 jquery 这样做：
$(function () {
$('<%= fileUploadCV.ClientID %>').change(function () {
//because this is single file upload I use only first index
var f = this.files[0]
//here I check if the file size is bigger than 8 MB (numbers below are in bytes)
if (f.size > 8388608 || f.fileSize > 8388608)
{
//show an alert to the user
alert("Allowed file size exceeded. (Max. 8 MB)")
//and RESET file upload control
this.value = null;
}
})
});
