Regular expressions - JavaScript | MDN

Regular expressions are patterns used to match character combinations in strings. In JavaScript, regular expressions are also objects. These patterns are used with the exec() and test() methods of RegExp, and with the match(), matchAll(), replace(), replaceAll(), search(), and split() methods of String. This chapter describes JavaScript regular expressions. It provides a brief overview of each syntax element. For a detailed explanation of each one's semantics, read the regular expressions reference.