I$\text{'}$m having a problem with my html and JavaScript code. In my html file a have an input:

and I$\text{'}$m trying to add an event listener to it in JS$.$

this is what I wrote in the JS file:

var calculate $=$ document.getElementById$($calcBtn$)$;

calculate.addEventListener$(\text{'}$click$\text{'},$ calcHours$)$;

but for some reason it's saying that the calcBtn is not defined.

this is the error I$\text{'}$m getting in the console:

Uncaught ReferenceError: calcBtn is not defined

How can I fix this problem? and what exactley did I do wrong?

I need an answer as soon as possible, please!