Very useful regular expression that developers must know

Regular expression for detecting HTML tags

/^<([a-z]+)([^<]+)*(?:>(.*)<\/\1>|\s+\/>)$/

Regular expression for matching an email ahandy-contentddress

/^([a-z0-9_\.-]+)@([\da-z\.-]+)\.([a-z\.]{2,6})$/

Regular expression for matching an url

/^(https?:\/\/)?([\da-z\.-]+)\.([a-z\.]{2,6})([\/\w \.-]*)*\/?$/

Regular expression for matching HTML BR tag

/<br\s*\/?>/g