Regex

A sequence of characters defining a search pattern, used to validate, find, or replace text. A regex like /^[a-z0-9]+@[a-z]+\.com$/ validates email format.

Regex appears in form validation, search features, and data processing. Understanding the basics helps you read code, configure tools, and communicate requirements precisely.

A founder's signup form uses a regex to validate phone numbers before submission, catching errors instantly without an API call.