Reference
Regex Syntax A reference for the core regular-expression syntax: classes, quantifiers, anchors, and groups.
G By Gampangin · Published July 8, 2026 · Updated September 27, 2026 · Reviewed by Gampangin · 1 min read · Regex AI-assisted draft. Editorial responsibility: Gampangin .
A regular expression is a small language for describing text patterns. The core building blocks are character classes, quantifiers, anchors, and groups.
01 Core building blocksCharacter classes: [abc], [^abc], and shorthand such as \d and \w. Quantifiers: *, +, ?, and {m,n}, greedy or lazy. Anchors: ^ and $, with multiline behavior controlled by flags. Groups: capturing ( ) and non-capturing (?: ). Flags change meaning
The same pattern matches differently with the global, case-insensitive, multiline, or dotAll flags.
02 LimitationsThis is not a complete ECMAScript specification and omits engine-specific extensions.
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