Hi there,
I would need javascript code to check extension of uploaded file.
File upload in not mandatory, but I need script to check extension and allow only JPG, BMP, PGN and other Image files.

Link to the example: http://www.empire-elements.co.uk/mdf...line-form.html

Thank you all

Try this:
Put this code in the head section of your page

<script language="JavaScript">
    extArray = new Array(".jpg", ".png", ".bmp");
    function LimitAttach(form, file) {
    allowSubmit = false;
    if (!file) return;
    while (file.indexOf("\\") != -1)
    file = file.slice(file.indexOf("\\") + 1);
    ext = file.slice(file.indexOf(".")).toLowerCase();
    for (var i = 0; i < extArray.length; i++) {
    if (extArray[i] == ext) { allowSubmit = true; break; }
    }
    if (allowSubmit) return true;
    else
    alert("Please only upload files that end in types:  "
    + (extArray.join("  ")) + "\nPlease select a new "
    + "file to upload and submit again.");
    return false;
    }
    //  End -->
</script>

Use this for your submit button on your upload form:

<input type='submit' name='Submit' value='Upload' onclick='return LimitAttach(this.form, this.form.FILE_FIELD.value)

Change FILE_FIELD to the name of the upload field on your form.

Could you please help me to add it to existing javascript that i have for this form ?

function validate(f)
{
if (f.reg1.value=="") {
alert("Please add Vinyl Finishes!");
f.reg1.focus();
return false;
}
if (f.reg2.value=="") {
alert("Please add Rout Styles Doors!");
f.reg2.focus();
return false;
}
if (f.reg3.value=="") {
alert("Please add Rout Styles Drawer Fronts!");
f.reg3.focus();
return false;
}
var a = parseInt(f.phone.value,10);
if (! a || a <= 0 ) {
alert("Please put your telephone number!");
f.phone.focus();
return false;
}
if (f.delivery.value=="") {
alert("Please add delivery address!");
f.delivery.focus();
return false;
}
if(f.pravidla.checked == false){
alert("Sorry, you must confirm that order details are correct");
f.pravidla.focus();
return false;
}
if(f.pravidla2.checked == false){
alert("Sorry, you must agree to our terms and conditions");
f.pravidla2.focus();
return false;
}
if(f.name.value == "") {
alert("Please add your name");
f.name.focus();
return false;
}
charset=new RegExp("^[^.]+(\.[^.]+)*@([^.]+[.])+[a-z]{2,3}$");
if (!charset.test(f.email.value))
{
window.alert("Please add valid email address!");
f.email.focus();
return false;
}

return true;
}

function validate(f) 
{
if (f.reg1.value=="") {
alert("Please add Vinyl Finishes!");
f.reg1.focus();
return false;
} 
if (f.reg2.value=="") {
alert("Please add Rout Styles Doors!");
f.reg2.focus();
return false;
} 
if (f.reg3.value=="") {
alert("Please add Rout Styles Drawer Fronts!");
f.reg3.focus();
return false;
} 
var a = parseInt(f.phone.value,10);
if (! a || a <= 0 ) {
alert("Please put your telephone number!");
f.phone.focus();
return false;
} 
if (f.delivery.value=="") {
alert("Please add delivery address!");
f.delivery.focus();
return false;
} 
if(f.pravidla.checked == false){
alert("Sorry, you must confirm that order details are correct");
f.pravidla.focus();
return false;
} 
if(f.pravidla2.checked == false){
alert("Sorry, you must agree to our terms and conditions");
f.pravidla2.focus();
return false;
} 
if(f.name.value == "") {
alert("Please add your name");
f.name.focus();
return false;
}
charset=new RegExp("^[^.]+(\.[^.]+)*@([^.]+[.])+[a-z]{2,3}$");
if (!charset.test(f.email.value))
{
window.alert("Please add valid email address!");
f.email.focus();
return false;
}

return true; 
}


function LimitAttach(form, file) {
    extArray = new Array(".jpg", ".png", ".bmp");
    allowSubmit = false;
    if (!file) return;
    while (file.indexOf("\\") != -1)
    file = file.slice(file.indexOf("\\") + 1);
    ext = file.slice(file.indexOf(".")).toLowerCase();
    for (var i = 0; i < extArray.length; i++) {
    if (extArray[i] == ext) { allowSubmit = true; break; }
    }
    if (allowSubmit) return true;
    else
    alert("Please only upload files that end in types:  "
    + (extArray.join("  ")) + "\nPlease select a new "
    + "file to upload and submit again.");
    return false;
}

A rather useful bit, thanks! I recently got the same problem going on. In addition to checking the file extension prior to uploading, is it possible to use javascript to check the file size of the file to be uploaded? You know, web servers usually has this uploading limit I don't want my users to upload file that's too big and only after 20 minutes of uploading that they find out the uploading failed due to this.

I don't know much about javascript but my guess is that it's impossible as javascript is unable to access the file system? Or isit?