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

If regexp is not a RegExp object and does not have a 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.


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

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


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

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


ECMAScript Language Specification

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See also