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.
Syntax
search(regexp)
Parameters
regexp: A regular expression object, or any object that has a
Symbol.searchmethod.If
regexpis not aRegExpobject and does not have aSymbol.searchmethod, it is implicitly converted to a RegExp by usingnew 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[@@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().
- If you only want to know if it exists, use the RegExp.prototype.test method, which returns a boolean.
- If you need the content of the matched text, use String.prototype.match or RegExp.prototype.exec.
Examples
Using 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(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