title: Detect if function is native to browser
body: <p>I am trying to iterate over all the globals defined in a website, but in doing so I am also getting the native browser functions.  </p>
  
  <pre><code>var numf=0; var nump=0; var numo=0; 
  for(var p in this) { 
      if(typeof(this[p]) === "function"){
          numf+=1;
          console.log(p+"()");
      } else if(typeof p != 'undefined'){
          nump+=1;
          console.log(p);
      } else { 
          numo+=1;
          console.log(p);
      }
  }
  </code></pre>
  
  <p>Is there a way to determine if a function is native to the browser or created in a script?</p>