Introduction to Regular Expressions (JavaScript)

These topics introduce the concept of regular expressions and explain how to create and use them.

A regular expression describes one or more strings to match when you search a body of text. The expression serves as character pattern to compare with the text being searched. You can use regular expressions to search for patterns in a string, replace text, and extract substrings.

• Uses for Regular Expressions
  Illustrates circumstances that would benefit from the use of regular expressions.

• Creating a Regular Expression
  Explains how to construct a regular expression.

• Regular Expression Programming
  Provides code examples that show how to search for patterns in a string, replace text, and extract substrings.

• Regular Expression Syntax
  Summarizes the elements that make up the regular expression syntax and provides examples.

• Lists of Matching Characters
  Describes how to match a single character from a list of characters or range of characters.

• Quantifiers
  Explains how to search for a character or set of characters that is repeated a specific number of times.

• Anchors
  Explains how to specify that a pattern that you are searching for has to appear either at the start or end of the searched string, or the start or end of a line or word in the searched string.

• Alternation and Subexpressions
  Explains how to specify a choice between two or more alternatives in a regular expression. Also explains how to create a subexpression.

• Backreferences
  Explains how to refer to a subexpression from within a regular expression, and from within a replacement string.

• JavaScript User's Guide
  Provides information about how to use JavaScript and includes a guide to regular expressions.