What are Regular Expressions?īefore we dive into JavaScript's API for working with RegEx, let's first take a look at Regular Expressions themselves. In this guide, we'll be looking at Regular Expressions in JavaScript, the usage of the RegExp class, as well as the exec() and test() methods.Īfterwards, we'll take a look at some of the methods implemented with the String object - match(), search() and replace(), which work with Regular Expressions as a shorter alternative to using the RegExp class. If you are not comfortable with writing them, you can always use RegEx testing websites such as or - which visually display the effects of your expressions on given strings. Obviously, the prerequisite to working with these is knowledge of Regular Expressions.
In JavaScript, the RegExp class used to represent Regular Expressions and can be coupled with a few methods which make matching patterns easier. While there are many pattern-matching libraries and approaches - a time-tested approach is using Regular Expressions to define a set of rules a certain string has to follow in order to match that pattern. In the most common cases, you'll need these to validate emails, user inputs, file names, or most kinds of input strings. Matching strings or string patterns can be a real struggle.
