Regular expression detects whether the email address entered by the user is legitimate

In the development of the registration system, the need to detect the user input email address is legitimate, can use regular expression to detect, below a small example, I hope to help you

In the registration system development, the need to detect the user input email address is legitimate, can be detected in JS or PHP, but the difference is not small, can use regular expression to detect. Here is an example of JS: The code is as follows: function validateemail (email) {var re =/^ ([^<> () [].,;:s@]]+ (. [ ^<> () [].,;:s@ "]+) *) | (  ".+")) @ ([[0-9]{1,3}. [0-9] {1,3}. [0-9] {1,3}. [0-9] {1,3}]) | (([a-za-z-0-9]+.)  +[a-za-z]{2,})) $/;  return re.test (email); }