Regular Expressions (Regex) Cheat Sheet

#Dasar Regex

#Membuat Regex

Dua cara bikin pattern regex di JavaScript.

javascript

// Literal notation (preferred untuk pattern statis)
const emailPattern = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
 
// Constructor (untuk pattern dinamis)
const searchTerm = "hello";
const dynamicPattern = new RegExp(searchTerm, "gi");

#Test dan Match

javascript

const text = "Halo, email aku adalah test@example.com";
 
// test() - return boolean
emailPattern.test(text); // true
 
// match() - return array match atau null
text.match(/\b\w+@

#Character Classes

#Predefined Classes

Tabel class yang paling sering dipake.

javascript

// \d - digit (0-9)
/\d+/.test("abc123");  // true
 
// \D - non-digit
/\D/.test("123");      // false
 
// \w - word character (a-z, A-Z, 0-9, _)

#Custom Character Sets

javascript

// [abc] - salah satu a, b, atau c
/[aeiou]/.test("hello"); // true
 
// [a-z] - range huruf kecil
/[a-z]/.test("ABC");    // false
 
// [A-Za-z0-9] - alphanumeric
/[A-Za-z0-9]+

#Anchors

#Posisi Matching

javascript

// ^ - awal string
/^Hello/.test("Hello World");  // true
/^World/.test("Hello World"); // false
 
// $ - akhir string
/

#Quantifiers

#Jumlah Pengulangan

javascript

// * - 0 atau lebih
/ab*c/.test("ac");      // true (b 0 kali)
/ab*c/.test("abbbc");   // true

#Greedy vs Lazy

javascript

const html = '<div class="a">Hello</div><div class="b">World</div>';
 
// Greedy (default) - match sebanyak mungkin
html.match(/<div.*>/);
// '<div class="a">Hello</div><div class="b">World</div>'
 
// Lazy (?) - match sesedikit mungkin
html.match(/

#Groups dan Backreferences

#Capturing Groups

javascript

// (pattern) - capturing group
const date = "2024-06-21";
const match = date.match(/(\d{4})-(\d{2})-(\d{2})/);

#Non-Capturing Groups

javascript

// (?:pattern) - group tanpa capture
"abc123".match(/(?:abc)(\d+)/);
// match[1] = "123" (hanya yang di-capture)
 
// Berguna untuk alternation tanpa capture
const yes = "yes yesn't";
yes.match(/(?:yes|

#Backreferences

javascript

// \1, \2, dst - referensi ke group sebelumnya
// Match kata berulang
/\b(\w+)\s+\1\b/.test("hello hello"); // true
/\b(\w+)\s+\1\b/

#Lookaround

#Lookahead dan Lookbehind

javascript

// (?=pattern) - positive lookahead (setelah posisi ini, harus match)
/\d+(?=px)/.test("100px");   // true
/\d+(?=px)/.test("100em");

#Contoh Lookaround Real-world

javascript

// Password: minimal 8 char, ada huruf besar, huruf kecil, dan angka
const passwordPattern = /^(?=.*[a-z])(?=.*[A-Z])(?=.*\d).{8,}$/;
passwordPattern.test(

#Flags

javascript

// g - global (match semua, bukan cuma pertama)
"aaa".match(/a/g);  // ["a", "a", "a"]
"aaa".match(/a/);   // ["a"]
 
// i - case insensitive

#Alternation

javascript

// | = OR
/cat|dog|bird/.test("I have a dog"); // true
 
// Grouping dengan alternation
/(cat|dog)s?/.test("cats"); // true

#Common Patterns

#Email

javascript

// Sederhana
/^[^\s@]+@[^\s@]+\.[^\s@]+$/
 
// Lebih ketat (RFC 5322近似)
/^[a-zA-Z0-9.!#$%&'*+/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]

#URL

javascript

// HTTP/HTTPS URL
/^https?:\/\/(www\.)?[-a-zA-Z0-9@:%._\+~#=]{1,256}\.[a-zA-Z0-9()]{1,6}\b([-a-zA-Z0-9()@:%_\+.~#?&//=]*)$

#Phone Number (Indonesia)

javascript

// Format Indonesia: +62 atau 08
/^(\+62|62|0)8[1-9][0-9]{6,11}$/
 
// Match nomor di teks
/(\+62|62|0)8[1-9]\d{6,11}/g

#IP Address

javascript

// IPv4
/^((25[0-5]|2[0-4]\d|[01]?\d\d?)\.){3}(25[0-5]|2[0-4]\d|[01]?\d\d?)$/

#Date

javascript

// YYYY-MM-DD
/^\d{4}-(0[1-9]|1[0-2])-(0[1-9]|[12]\d|3[01])$/
 
// DD/MM/YYYY
/^(0[1-9]|[12]\d|3[01]

#Slug

javascript

/^[a-z0-9]+(?:-[a-z0-9]+)*$/
// "hello-world-123" match
// "Hello World" tidak match

#Hex Color

javascript

/^#?([0-9a-fA-F]{3}|[0-9a-fA-F]{6})$/
// "#fff" match
// "#1a2b3c" match
// "#ggg" tidak match

#String Methods dengan Regex

#Replace dengan Callback

javascript

// Replace dengan function
"hello world".replace(/(\w+)/g, (match, word) => {
  return word.charAt(0).toUpperCase() + word.

#Split dengan Capture Groups

javascript

// Groups ikut masuk ke hasil split
"a,b,c".split(/(,)/);
// ["a", ",", "b", ",", "c"]

#Regex di Bahasa Lain

#Python

python

import re
 
# Search
re.search(r'\d+', 'abc123')  # <Match object>
 
# Find all
re.findall(r'\d+', 'a1b2c3')  # ['1', '2', '3']

#Golang

import "regexp"
 
re := regexp.MustCompile(`\d+`)
 
// Match
re.MatchString("abc123") // true
 
// Find
re.FindString("abc123def") // "123"

#Glossary

Pattern: Ekspresi regex yang ngejelasin format teks yang dicari.
Anchor: Penanda posisi (^ awal, $ akhir, \b word boundary) yang ngga match karakter, cuma posisi.
Quantifier: Nentuin berapa kali suatu pattern harus muncul (* + ? ).
Greedy: Default behavior regex yang match sebanyak mungkin. Tambah ? buat lazy.
Capturing Group: Pattern dalam tanda kurung yang hasil match-nya bisa diakses.
Lookahead/Lookbehind: Assertion yang ngecek pattern tanpa consume karakter.
Flag: Modifier yang ngubah cara regex match (g global, i case-insensitive, m multiline).
Backreference: Referensi ke capturing group sebelumnya (\1, \2, dst).

Regular Expressions (Regex) Cheat Sheet

Baca Cheat Sheet Lengkap

Regular Expressions (Regex) Cheat Sheet

Baca Cheat Sheet Lengkap

#Dasar Regex

#Membuat Regex

#Test dan Match

#Character Classes

#Predefined Classes

#Custom Character Sets

#Anchors

#Posisi Matching

#Quantifiers

#Jumlah Pengulangan

#Greedy vs Lazy

#Groups dan Backreferences

#Capturing Groups

#Non-Capturing Groups

#Backreferences

#Lookaround

#Lookahead dan Lookbehind

#Contoh Lookaround Real-world

#Flags

#Alternation

#Common Patterns

#Email

#URL

#Phone Number (Indonesia)

#IP Address

#Date

#Slug

#Hex Color

#String Methods dengan Regex

#Replace dengan Callback

#Split dengan Capture Groups

#Regex di Bahasa Lain

#Python

#Golang

#Glossary