Javascript Plugin Development (external JS files vs wp_enqueue_script)

Hi, I’m developing a plugin for work and I’m basically learning how to develop plugins for the first time. I have a question about using javascript hardcoded in the main php file for the plugin and linking to the external javascript files.

Basically I can use document.write() if I hard code it into the plugin but, if I try to use wp_enqueue_script the javascript works but, document.write doesn’t seem to work.

So this works

echo '<h1>Clean Post Search Settings</h1></p>
<p>		<h2>Add/Edit Topics</h2>';?><br />
		<script><br />
		document.open();<br />
		document.write("<h1>Main title</h1>");<br />
		document.close();<br />
		</script></p>
<p>

But, document.write doesn’t work here

PHP

</p>
<p>function cps_zt_settings_page(){<br />
	echo '<h1>Clean Post Search Settings</h1></p>
<p>		<h2>Add/Edit Topics</h2>';<br />
		wp_enqueue_script(cps_zt_js);<br />
}<br />

External Javascript file

<br />
document.open();<br />
document.write("<h1>Hello World</h1>");<br />
document.close();<br />