JavaScript: The Definitive Guide, 6th Edition

Chapter 10. Pattern Matching with Regular Expressions

A regular expression is an object that describes a pattern of characters. The JavaScript RegExp class represents regular expressions, and both String and RegExp define methods that use regular expressions to perform powerful pattern-matching and search-and-replace functions on text. JavaScript’s regular expression grammar is a fairly complete subset of the regular-expression syntax used by Perl 5, so if you are an experienced Perl programmer, you already know how to describe patterns in JavaScript.^[17]

This chapter begins by defining the syntax that regular expressions use to describe textual patterns. It then moves on to describe the String and RegExp methods that use regular expressions.

^[17] Perl regular expression features that are not supported by ECMAScript include the s (single-line mode) and x (extended syntax) flags; the \a, \e, \l, \u, \L, \U, \E, \Q, \A, \Z, \z, and \G escape sequences; the (?<= positive look-behind anchor and the (?<! negative look-behind anchor; and the (?# comment and the other extended (? syntaxes.