javascript - Checking the referrer

Question

I'm using this to check if someone came from Reddit, however it doesn't work.

var ref = document.referrer;
if(ref.match("/http://(www.)?reddit.com(/)?(.*)?/gi"){
    alert('You came from Reddit');
} else {
    alert('No you didn't');
}

Suggestions on the regular expression are most welcome too.

Answer 1

Try this:

if (ref.match(/^https?://([^/]+.)?reddit.com(/|$)/i)) {
  alert("Came from reddit");
}

The regexp:

/^           # ensure start of string
 http        # match 'http'
 s?          # 's' if it exists is okay
 ://       # match '://'
 ([^/]+.)? # match any non '/' chars followed by a '.' (if they exist)
 reddit.com # match 'reddit.com'
 (/|$)      # match '/' or the end of the string
/i           # match case-insenitive