require is not defined - Create array of every file in a directory

Here is a part of my <script> in the htlm

<script>
var fs = require('fs');
var images = fs.readdirSync('/i/cats/');
</script>

I host my website at 000webhost (free version)

My probles is gives me a ReferenceError, 'require is not defined'

To not make confusion, i am trying to find the files on the server, not the client-side