Regex Special Characters You Must Escape

Some characters mean something specific to the regex engine. If you want to match them literally — not as pattern syntax — you must escape them with a backslash.

The 12 metacharacters

These characters have special meaning in most regex flavors:

. * + ? ^ $ { } [ ] ( ) | \

Character	Role in regex
.	Match any character (except newline by default)
*	Zero or more of the preceding
+	One or more of the preceding
?	Zero or one; also makes quantifiers lazy
^	Start of string (or line with m flag)
$	End of string (or line with m flag)
{ }	Quantifier range: {2,5} means 2 to 5
[ ]	Character class: [a-z]
( )	Capture group
|	Alternation (OR)
\	Escape the next character

How to escape them

Prefix the character with \ to match it literally:

// Match a period, not "any character"
/3\.14/.test("3.14")  // true
/3\.14/.test("3X14")  // false

// Match a literal dollar sign
/\$100/.test("$100")  // true

// Match a literal backslash
/C:\\Users/.test("C:\\Users")  // true

Common mistake: URLs and file paths

URLs and paths are full of metacharacters. A naive pattern silently matches more than you expect:

// ❌ The dot matches any character
/example.com/.test("exampleXcom")  // true — probably not what you wanted

// ✅ Escape the dot
/example\.com/.test("exampleXcom")  // false

In JavaScript string literals, escape twice

When building a regex from a string with new RegExp(), each backslash needs to be doubled — once for the string, once for the regex engine:

const pattern = new RegExp("\\$\\d+");  // matches "$42"
// Equivalent regex literal:
const re = /\$\d+/;

With a regex literal (/.../), one backslash is enough. With a string, you need two.

Test escaping live

Paste your pattern into the regex tester and see exactly which parts of your input match as you type. If a . is matching characters it shouldn't, you're missing the backslash.

For flag modifiers like g, i, and m, see regex flags explained. For a broader reference of useful patterns, see the regex cheat sheet.