String Methods for Pattern Matching

Until now, this chapter has discussed the grammar used to create regular expressions, but it hasn’t examined how those regular expressions can actually be used in JavaScript code. This section discusses methods of the String object that use regular expressions to perform pattern matching and search-and-replace operations. The sections that follow this one continue the discussion of pattern matching with JavaScript regular expressions by discussing the RegExp object and its methods and properties. Note that the discussion that follows is merely an overview of the various methods and properties related to regular expressions. As usual, complete details can be found in Part III.

Strings support four methods that use regular expressions. The simplest is search(). This method takes a regular-expression argument and returns either the character position of the start of the first matching substring or −1 if there is no match. For example, the following call returns 4:


If the argument to search() is not a regular expression, it is first converted to one by passing it to the RegExp constructor. search() does not support global searches; it ignores the g flag of its regular expression argument.

The replace() method performs a search-and-replace operation. It takes a regular expression as its first argument and a replacement string as its second argument. It searches the string on which it is called for matches with the specified ...

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