Text document not changing to html

I want to change the text in a text file called data.txt but I don't know how to change it with script. This is my code:

    $[document].ready[function[]{
        $["#btn"].click[function[]{
            $["#txt"].load["data.txt"];
            
        }];
    }];
 Save as in the Notepad menu. Name the file "index.htm" and set the encoding to UTF-8 [which is the preferred encoding for HTML files]. Tip: You can use either .htm or .html as file extension. There is no difference; it is up to you.