<!DOCTYPE html>
<html>
<body>
<form action="form_action.asp">
Select files: <input type="file" id="myFile" name="files">
<input type="submit">
</form>
<p>Click the "Try it" button to allow multiple values (files) for the file upload button.</p>
<p>Try selecting more than one file when browsing for files before and after you have clicked on the "Try it" button. <strong>Tip:</strong> hold down CTRL or the SHIFT key while select, to select multiple files.</p>
<button onclick="myFunction()">Try it</button>
<p id="demo"></p>
<script>
function myFunction() {
document.getElementById("myFile").multiple = true;
document.getElementById("demo").innerHTML = "The file upload button now accept multiple values.";
}
</script>
</body>
</html>