Hello. I'm new so please bear with me.
Basically, I want to define a certain variable and make it appear within a HTML code.

<input type="text" id="RANDOMTEXT">
var x = document.GetElementById("RANDOMTEXT");

I want to insert "RANDOMTEXT" within a HTML code, and it needs to auto-preview:

<font size="RANDOMTEXT">Hello</font>

Can anyone help me out? Thank you so much.