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Regular Expressions (Regex) Cheat Sheet Referensi cepat regex. Character classes, anchors, quantifiers, groups, lookaround, flags, dan common patterns. Perfect buat developer yang sering parsing dan validasi teks.
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Regular Expressions (Regex) Cheat Sheet - BelajarKoding | BelajarKoding
# Dasar Regex# Membuat RegexDua cara bikin pattern regex di 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" );
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 + @ Tabel class yang paling sering dipake.
// \d - digit (0-9) / \d + / . test ( "abc123" ); // true
// \D - non-digit / \D / . test ( "123" ); // false
// \w - word character (a-z, A-Z, 0-9, _) // [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] + // ^ - awal string / ^ Hello / . test ( "Hello World" ); // true / ^ World / . test ( "Hello World" ); // false
// $ - akhir string / // * - 0 atau lebih / ab * c / . test ( "ac" ); // true (b 0 kali) / ab * c / . test ( "abbbc" ); // true
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// (pattern) - capturing group const date = "2024-06-21" ; const match = date. match ( / ( \d {4} )-( \d {2} )-( \d {2} ) / ); // (?: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 | // \1, \2, dst - referensi ke group sebelumnya // Match kata berulang / \b ( \w + ) \s +\1\b / . test ( "hello hello" ); // true / \b ( \w + ) \s +\1\b / # Lookahead dan Lookbehind// (?=pattern) - positive lookahead (setelah posisi ini, harus match) / \d + (?=px) / . test ( "100px" ); // true / \d + (?=px) / . test ( "100em" ); # Contoh Lookaround Real-world// Password: minimal 8 char, ada huruf besar, huruf kecil, dan angka const passwordPattern = / ^ (?= . * [a-z] )(?= . * [A-Z] )(?= . * \d ) . {8,}$ / ; passwordPattern. test ( // g - global (match semua, bukan cuma pertama) "aaa" . match ( / a / g ); // ["a", "a", "a"] "aaa" . match ( / a / ); // ["a"]
// i - case insensitive // | = OR / cat | dog | bird / . test ( "I have a dog" ); // true
// Grouping dengan alternation / (cat | dog)s ? / . test ( "cats" ); // true
// Sederhana / ^ [ ^ \s@] + @ [ ^ \s@] + \. [ ^ \s@] +$ /
// Lebih ketat (RFC 5322近似) / ^ [a-zA-Z0-9.!#$%&'*+/=?^_`{|}~-] + @ [a-zA-Z0-9] (?: [a-zA-Z0-9-] // 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)// 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 // IPv4 / ^ ((25 [0-5] | 2 [0-4]\d | [01] ? \d\d ? ) \. ) {3} (25 [0-5] | 2 [0-4]\d | [01] ? \d\d ? ) $ / // 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] / ^ [a-z0-9] + (?:- [a-z0-9] + ) *$ / // "hello-world-123" match // "Hello World" tidak match / ^ # ? ( [0-9a-fA-F] {3}| [0-9a-fA-F] {6} ) $ / // "#fff" match // "#1a2b3c" match // "#ggg" tidak match # String Methods dengan Regex// Replace dengan function "hello world" . replace ( / ( \w + ) / g , ( match , word ) => { return word. charAt ( 0 ). toUpperCase () + word. # Split dengan Capture Groups// Groups ikut masuk ke hasil split "a,b,c" . split ( / (,) / ); // ["a", ",", "b", ",", "c"] import re
# Search re.search( r ' \d + ' , 'abc123' ) # <Match object>
# Find all re.findall( r ' \d + ' , 'a1b2c3' ) # ['1', '2', '3']
import " regexp "
re := regexp. MustCompile ( `\d+` )
// Match re. MatchString ( "abc123" ) // true
// Find re. FindString ( "abc123def" ) // "123"
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). \w
+
\.
\w
+\b
/
g
);
// ["test@example.com"]
// matchAll() - iterator untuk semua matches dengan groups
const matches = [ ... text. matchAll ( / ( \w + )@( \w + ) \. ( \w + ) / g )];
// matches[0][1] = "test", matches[0][2] = "example", matches[0][3] = "com"
// search() - return index pertama match
text. search ( / email / ); // 6
// replace() - ganti match
text. replace ( / test@ / , "admin@" );
// "Halo, email aku adalah admin@example.com"
// split() - pisah string berdasarkan pattern
"a,b;c.d" . split ( / [,;.] / ); // ["a", "b", "c", "d"]
/ \w + / . test ( "hello_123" ); // true
// \W - non-word character
/ \W / . test ( "hello!" ); // true (match "!")
// \s - whitespace (space, tab, newline)
/ \s / . test ( "hello world" ); // true
// \S - non-whitespace
/ \S / . test ( " " ); // false
// . - any character (kecuali newline)
/ a . b / . test ( "axb" ); // true
// Escape special chars: . * + ? ^ $ { } [ ] \ | ( )
/ \$ \d + \. \d + / . test ( "$19.99" ); // true
/
.
test
(
"abc123"
);
// true
// [^abc] - negation, BUKAN a, b, atau c
/ [ ^ aeiou] / . test ( "a" ); // false
// [0-9a-fA-F] - hexadecimal
/ ^ [0-9a-fA-F] +$ / . test ( "deadBEEF" ); // true
World
$
/
.
test
(
"Hello World"
);
// true
// \b - word boundary
/ \b cat \b / . test ( "the cat sat" ); // true
/ \b cat \b / . test ( "category" ); // false
/ \b cat / . test ( "catch" ); // true (cat di awal kata)
// \B - non-word boundary
/ \B cat / . test ( "concatenate" ); // true (cat di tengah kata)
// ^ dan $ bersamaan = full string match
/ ^ \d {4}$ / . test ( "2024" ); // true
/ ^ \d {4}$ / . test ( "20241" ); // false
// + - 1 atau lebih
/ ab + c / . test ( "ac" ); // false
/ ab + c / . test ( "abc" ); // true
// ? - 0 atau 1 (opsional)
/ colou ? r / . test ( "color" ); // true
/ colou ? r / . test ( "colour" ); // true
// {n} - tepat n kali
/ \d {4} / . test ( "1234" ); // true
/ \d {4} / . test ( "123" ); // false
// {n,} - minimal n kali
/ \d {2,} / . test ( "12345" ); // true
// {n,m} - antara n dan m kali
/ \d {2,4} / . test ( "123" ); // true
/ \d {2,4} / . test ( "1" ); // false
/ \d {2,4} / . test ( "12345" ); // false (lebih dari 4)
<div
.
*?
>
/
);
// '<div class="a">'
// Contoh lain
"aaa" . match ( / a + / ); // ["aaa"] greedy
"aaa" . match ( / a +? / ); // ["a"] lazy
// match[0] = "2024-06-21"
// match[1] = "2024" (year)
// match[2] = "06" (month)
// match[3] = "21" (day)
// Named groups (?<name>pattern)
const namedMatch = date. match ( / (?< year > \d {4} )-(?< month > \d {2} )-(?< day > \d {2} ) / );
namedMatch.groups.year; // "2024"
namedMatch.groups.month; // "06"
namedMatch.groups.day; // "21"
no)n
?
/
g
);
// ["yes", "yesn't"] - wait, n't is separate
.
test
(
"hello world"
);
// false
// Match tanda kutip yang konsisten
/ ( ['"] )( . *? ) \1 / . test ( '"hello"' ); // true
/ ( ['"] )( . *? ) \1 / . test ( "'hello'" ); // true
/ ( ['"] )( . *? ) \1 / . test ( '"hello \' ' ); // false (beda quote)
// false
// (?!pattern) - negative lookahead (setelah ini, TIDAK boleh match)
/ \d + (?!px) / . test ( "100em" ); // true
/ \d + (?!px) / . test ( "100px" ); // false
// (?<=pattern) - positive lookbehind (sebelum posisi ini, harus match)
/ (?<= \$ ) \d + / . exec ( "$100" ); // ["100"]
/ (?<= \$ ) \d + / . exec ( "100" ); // null
// (?<!pattern) - negative lookbehind (sebelum ini, TIDAK boleh match)
/ (?<! \$ ) \b \d +\b / . exec ( "$100" ); // null (ada $ sebelum angka)
/ (?<! \$ ) \b \d +\b / . exec ( "100" ); // ["100"]
"Password1"
);
// true
passwordPattern. test ( "password" ); // false
// Angka dengan thousand separator (kecuali 4 digit di awal)
/ \B (?=( \d {3} ) + (?! \d )) / g ;
"1234567" . replace ( / \B (?=( \d {3} ) + (?! \d )) / g , "." );
// "1.234.567"
"Hello" . match ( / hello / i ); // ["Hello"]
// m - multiline (^ dan $ match per line)
"a \n b" . match ( / ^ b / m ); // ["b"]
"a \n b" . match ( / ^ b / ); // null
// s - dotall (. match newline juga)
"a \n b" . match ( / a . b / s ); // ["a\nb"]
"a \n b" . match ( / a . b / ); // null (tanpa s, . ngga match \n)
// y - sticky (match mulai dari lastIndex)
const sticky = / abc / y ;
sticky.lastIndex = 0 ;
sticky. test ( "abcabc" ); // true
sticky.lastIndex = 3 ;
sticky. test ( "abcabc" ); // true
// u - unicode
/ ^ \u {1F600} $ / . test ( "😀" ); // true (unicode mode)
// Di dalam character class, | artinya literal pipe
/ [|] / . test ( "a|b" ); // true
{0,61}
[a-zA-Z0-9]
)
?
(?:
\.
[a-zA-Z0-9]
(?:
[a-zA-Z0-9-]
{0,61}
[a-zA-Z0-9]
)
?
)
*$
/
/
// Extract URLs dari teks
const urlRegex = / https ? : \/\/ [ ^ \s] + / g ;
// IPv6 (simplified)
/ ^ ( [0-9a-fA-F] {1,4} :) {7} [0-9a-fA-F] {1,4}$ /
)
\/
(0
[1-9]
|
1
[0-2]
)
\/
\d
{4}$
/
slice
(
1
);
});
// "Hello World"
// Swap nama
"Doe, John" . replace ( / ( \w + ), \s * ( \w + ) / , "$2 $1" );
// "John Doe"
# Substitute
re.sub( r ' \d + ' , 'N' , 'a1b2c3' ) # 'aNbNcN'
# Split
re.split( r ' [,;] ' , 'a,b;c' ) # ['a', 'b', 'c']
# Named groups
m = re.search( r ' ( ?P<year> \d {4} ) - ( ?P<month> \d {2} ) ' , '2024-06' )
m.group( 'year' ) # '2024'
m.group( 'month' ) # '06'
// Find all
re. FindAllString ( "a1b2c3" , - 1 ) // ["1", "2", "3"]
// Replace
re. ReplaceAllString ( "a1b2" , "N" ) // "aNbN"
