Difference is Regex shorthand

JavaScript
1

Can someone please explain the difference between /\s/ and /\w/ or /\S/ and /\W/ ?

Here’s the code in question :

let sample = "Whitespace is important in separating words";
let countNonWhiteSpace = /\s/g; // Change this line
let result = sample.match(countNonWhiteSpace);

console.log(sample.match(countNonWhiteSpace));
2

/\s/ matches any whitespace (space, tab, returns, etc.)
/\S/ matches anything not a whitespace
/\w/ matches anything a “word” character (letter, number, underscore)
/\W/ matches anything not a “word” character

3

That I understand, sort of. In the above, /\W/ does the same as /\s/ and /\S/ the same as /\w/. My question is what makes choosing one over the other any different if the outcome will be the same?

4

No, /\W/ and /\s/ are not the same. They are close but not the same. “Not a ‘word’ character” and “whitespace” are not the same thing. Close but not the same. There are plenty of characters that are not word characters that are also not whitespace, for example:

!@#$%^&*()-+=`~{}|;:'",<.>/?

All of those characters will be matched by /\W/ and not /\s/. And those are just the characters in a regular keyboard.

They are just two different ways to refer to characters that overlap somewhat. Which you use depends on what you need.

5

There are maybe about 20 space characters defined, possibly a lot more (actual exact number seems to be unknown).
There are maybe 15,000-20,000 non-word characters (again, actual exact number seems to be unknown).

(this is assuming Unicode is being used)

> /\s/u.test("💩")
false # poo is not a space
> /\W/u.test("💩")
true # poo is a non-word character

but

> /\w/u.test("💩")
false # poo is not a word character
> /\S/u.test("💩")
true # poo is a non-space character
6

Thank you both. it makes complete sense now.