String.prototype.search()

The search() method of String values executes a search for a match between a regular expression and this string, returning the index of the first match in the string.

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Syntax

js
search(regexp)

Parameters

regexp

A regular expression object, or any object that has a Symbol.search method.

If regexp is not a RegExp object and does not have a Symbol.search method, it is implicitly converted to a RegExp by using new RegExp(regexp).

Return value

The index of the first match between the regular expression and the given string, or -1 if no match was found.

Description

The implementation of String.prototype.search() itself is very simple — it simply calls the Symbol.search method of the argument with the string as the first parameter. The actual implementation comes from RegExp.prototype[Symbol.search]().

The g flag of regexp has no effect on the search() result, and the search always happens as if the regex's lastIndex is 0. For more information on the behavior of search(), see RegExp.prototype[Symbol.search]().

When you want to know whether a pattern is found, and also know its index within a string, use search().

Examples

The following example searches a string with two different regex objects to show a successful search (positive value) vs. an unsuccessful search (-1).

js
const str = "hey JudE";
const re = /[A-Z]/;
const reDot = /[.]/;
console.log(str.search(re)); // returns 4, which is the index of the first capital letter "J"
console.log(str.search(reDot)); // returns -1 cannot find '.' dot punctuation

Specifications

Specification
ECMAScript Language Specification
# sec-string.prototype.search

Browser compatibility

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See also