JavaScript正则表达式-如何只允许一个连字符？

Question

I have the following jscript code:

 var email = /^[a-z0-9'*+/=?^_`{|}~-]+(?:\.[a-z0-9'*+/=?^_`{|}~-]+)*@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?$/;

  if (s.match(email)) {
        return true;
  } else {
        return false;
  }

Now the end users are saying that they want "-" in the local part of the email address. (i didn't even know that was legit) But I need to prevent multiple hyphens I think - as per http://rumkin.com/software/email/rules.php And also I don't think it can start with a hyphen.

But i'm not sure how to change this code to accomplish that.

What I've tried

var email = /^[a-z0-9'*+/=?^_`{|}~-]+(?:\.\-[a-z0-9'*+/=?^_`{|}~-]+)*@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?$/;

That allows me to enter a hyphen, but it doesn't limit it to one.

Answer 1

You are not restricted to do everything in one regex:

var email = /^[a-z0-9'*+\/=?^_`{|}~-]+(?:\.[a-z0-9'*+\/=?^_`{|}~-]+)*@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?$/;
if (!s.match(email)) return false;

if (s[0] == '-') return false;
if (s[s.length-1] == '-') return false;
if (s.indexOf('--') != -1) return false;
return true;