By default, when clicking a file input (
<input type="file" />) the browser will list all files in the destination folder.
The file input provides the accept attribute which hints the browser to list particular file types. The attribue value can be one or many file extensions, MIME types, separated by a comma.
For example, the input asking users for choosing an avatar looks like:
accept=".png, .jpg, .jpeg"
<!-- Or -->
accept attribute does NOT prevent user from selecting a file whose type isn't in the list. Do NOT use it to validate the selected file.