JavaScript RegExp Whitespace Metacharacter (\s)

What Is \s?

\s matches one whitespace character: space, tab, newline, and related separators. Use it to detect gaps, split words, or normalize messy spacing.

\s  → one whitespace (space, \t, \n, \r, \f, \v, …)
\S  → one non-whitespace (inverse)

/\s/.test("hello")        → false
/\s/.test("hello world")  → true
"a  b".replace(/\s+/g, " ") → "a b"

How to Use \s

Match separators once, or use + when a whole run of whitespace matters.

1. Start with /\s/ to ask “is there any whitespace?”
2. Add + for runs: /\s+/ matches one or more separators.
3. Use split(/\s+/) to break text into words.
4. Use replace(/\s+/g, " ") to normalize spacing.

Pseudocode

pattern has "\s"
read next character ch from the string

if ch is whitespace:   // space, tab, newline, …
    accept match
else:
    fail this path

common actions:
  test(str)                 → true if any whitespace exists
  split(/\s+/)              → words between whitespace runs
  replace(/\s+/g, " ")      → collapse runs to one space

Cheat Sheet

Keep these patterns handy for everyday text cleanup.

Live Preview

Run common \s operations on sample strings with mixed whitespace.

text = "hello"
/\s/.test(text)
→ false

/* no whitespace present */

JavaScript Examples

Short, copy-ready snippets. Open DevTools Console, or use Try It Yourself for a live editor.

console.log(/\s/.test("hello"));       // false
console.log(/\s/.test("hello world")); // true
console.log(/\s/.test("a\tb"));        // true

false
true
true

const text = "one   two\tthree";

console.log(text.split(/\s+/));
// ["one", "two", "three"]

["one", "two", "three"]

const padded = "too    many     spaces";
const tabs = "hello\t\tworld";

console.log(padded.replace(/\s+/g, " ")); // "too many spaces"
console.log(tabs.replace(/\s+/g, " "));   // "hello world"

too many spaces
hello world

Performance Notes

Character-class style matches are cheap. Prefer \S when you want the visible parts, and \s when you want the separators.

Key Takeaways