Text Processingflags: g

Whitespace Trim (Leading & Trailing)

Match leading and/or trailing whitespace on a string — the regex equivalent of .trim().

Available in

JavaScript / ECMAScript code

jsJavaScript

const re = new RegExp("^\\s+|\\s+$", "g");
const input = "  hello world  ";
const matches = [...input.matchAll(re)];
console.log(matches.map(m => m[0]));

Uses `String.prototype.matchAll` for global iteration (Node 12+ / all modern browsers).

Python (re) code

pyPython

import re

pattern = re.compile(r"^\s+|\s+$")
input_text = "  hello world  "
for m in pattern.finditer(input_text):
    print(m.group(0))

Stdlib `re` module — no third-party dependency. Works on Python 3.6+.

Go (RE2) code

goGo

package main

import (
	"fmt"
	"regexp"
)

func main() {
	re := regexp.MustCompile(`^\s+|\s+$`)
	input := `  hello world  `
	for _, match := range re.FindAllString(input, -1) {
		fmt.Println(match)
	}
}

Uses `regexp.MustCompile` (panics on bad patterns at startup) and `FindAllString` for all matches.

Pattern

regexengine-agnostic

^\s+|\s+$   (flags: g)

Raw source: ^\s+|\s+$

How it works

^\s+ matches one or more whitespace characters at the start of the string. \s+$ matches one or more whitespace characters at the end. The alternation | with the g flag allows replacing both in a single pass.