When it comes to querying / selecting HTML elements via JavaScript, there are a couple of commonly used built-in methods that are worth knowing:

• document.getElementById('some-id'): Select a HTML element by its ID (selects only one element, since IDs should be unique)

• document.querySelector('<some-css-selector>'): Selects the first matching (!) HTML element that is met / selected by the provided CSS selector; The CSS selector can basically be any kind of valid CSS selector (e.g. ID selector, tag type selector, class selector, combined selectors etc.)

• document.querySelectorAll('<some-css-selector>'): Selects ALL matching HTML elements that are met / selected by the provided CSS selector

There also are a few lesser used selection methods, that you also should've heard about:

• document.getElementsByClassName('some-css-class'): Selects all HTML elements that have the provided CSS class

• document.getElementsByTagName('tag'): Selects all HTML elements that are of the provided HTML tag type