title: Using regex to split double hyphen but not single hyphen
body: <p>I have an html element id that looks like this:
  <code>dp__1-2--1-3</code></p>
  
  <p>I'm trying to use the JavaScript split() function to lop off and return the final '<code>1-3</code>'</p>
  
  <p>My regex skills are poor but a bit of searching around got me to this point:
  <code>
  var myId = "dp__1-2--1-3";
  var myIdPostFix = myId.split(/[\-\-]+/).pop();
  </code></p>
  
  <p>Unfortunately that returns me only the '<code>3</code>'.</p>
  
  <p>So my question is how do I split double hyphens but NOT single hyphens?</p>