Best way to determine if referrer was not from current domain?

I'm looking for the most elegant way to determine when a user hits a page on my website ( if they came in from any other source other than one of the pages from my own website. I'm assuming document.referrer is the only way but what would be the best approach? Regx, indexOf? Using javascript only!
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Dave BaldwinFixer of ProblemsCommented:
I think this will work for you.  Note that if you go directly to the page and not from a link on another page, there won't be a refferer.  You can replace the IP address in the example with a domain name or whatever it is you want to check.
<!DOCTYPE html>

<p>Click the button to display the referrer of the current document.</p>

<button onclick="myFunction()">Try it</button>

<p id="demo"></p>

<p id="result"></p>

function myFunction() {
    var x = document.referrer;
    document.getElementById("demo").innerHTML = x;
		pos = x.indexOf("");
		if(pos < 0) document.getElementById("result").innerHTML = "No Match found.";
		else document.getElementById("result").innerHTML = "Match is found.";

<a href="JSreferrer.html">JSreferrer.html</a>


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