What does const query selector In my code do? And what does do that const calculator = new calculator line 100-156

Question

Javascript pls explain detaly, I try to understand but cant
(CODE FROM YOUTUBE TUTORIAL)

https://code.sololearn.com/Wm7aQyKvKV1m/?ref=app

Answer 1

Your question is a clue that you've not wrote this code yourself: that's a bad practice to not at least quote for the original author ^^

'const' is the keyword used to declare a 'constant' value (an imutable -- read-only variable) as you use 'var' (or 'let') to declare variable...

'querySelector' is a method for retrieving reference to elements in the document (web page)...

'new Calculator' create an instance of the user defined class/prototype Calculator...

Answer 2

Thank you for your answer, I added that this is from YouTube tutorial. I am getting really really hard time understanding why I need these in my code, can you please tell me why I need this stuff in code??

Answer 3

https://developer.mozilla.org/en-US/docs/Web/API/Document/querySelector

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/new

https://developer.mozilla.org/en-US/docs/Learn/JavaScript/Objects