A regular expression or regex describes a pattern of characters. It can be used to perform powerful pattern-matching and search-and-replace functions on text.
Regular expression literals let pattern = /s$/;
Regular Expression Object
When typing into a search input, there is a delay before the typeahead results
appear. This functionality is controlled by a function called debounce().
The debounce() function delays processing of keyup event (events in general)
until the user stopped typing for a specified amount of time.
Five main values of CSS Positions:
position: static | relative | absolute | fixed | sticky
and helper properties for setting the coordinates of an element
top | right | bottom | left | z-index
These properties don't work without a declared position, or with static
z-index : As value increases, it moves in front of other elements,