<form name="abc">
<input type="file" onchange="isValidFile(this.value)"/>
</form>
<script>
function isValidFile(filename) {
if (getExtension(filename) != 'jpg') {
document.forms['abc'].reset();
alert("invalid Image");
}
}
function getExtension(filename) {
return filename.substring(filename.lastIndexOf('.') + 1);
}
</script>
جرب هذا