Text Processingflags: gm

Trailing Whitespace (Per Line)

Match trailing spaces and tabs at the end of each line — the regex linters use to flag dirty whitespace.

Available in

JavaScript / ECMAScript code

jsJavaScript

const re = new RegExp("[ \\t]+$", "gm");
const input = "good line\\nbad line  \\nfine";
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"[ \t]+$", re.MULTILINE)
input_text = "good line\nbad line  \nfine"
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(`(?m)[ \t]+$`)
	input := `good line\nbad line  \nfine`
	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

[ \t]+$   (flags: gm)

Raw source: [ \t]+$

How it works

[ \t]+ matches one or more space or tab characters. $ with the m (multiline) flag anchors to the end of EACH line, not the whole string. The g flag iterates so a multi-line string surfaces every offending line. Pair with `replace(re, '')` to strip.