Text Processingflags: gm

Single-Line Comment (// or #)

Match single-line comments using either the `//` (C-family) or `#` (shell, Python, Ruby, YAML) marker.

Available in

JavaScript / ECMAScript code

jsJavaScript

const re = new RegExp("(?://|#).*$", "gm");
const input = "var x = 1; // assignment\\n# python style\\ny = 2";
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"(?://|#).*$", re.MULTILINE)
input_text = "var x = 1; // assignment\n# python style\ny = 2"
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)(?://|#).*$`)
	input := `var x = 1; // assignment\n# python style\ny = 2`
	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

(?://|#).*$   (flags: gm)

Raw source: (?://|#).*$

How it works

(?://|#) is a non-capturing group matching either marker. .*$ matches the rest of the line up to the newline. The g flag finds every comment; the m flag makes $ anchor at line boundaries instead of just end-of-string.