Javascript isnull

Question

This is a really great function written in jQuery to determine the value of a url field:

  $.urlParam = function(name){
  var results = new RegExp('[\\?&]' + name + '=([^&#]*)').exec(window.location.href);
  return results[1] || 0;
  }
  // example.com?someparam=name&otherparam=8&id=6
  $.urlParam('someparam'); // name
  $.urlParam('id'); // 6
  $.urlParam('notavar'); // null

http://snipplr.com/view/11583/retrieve-url-params-with-jquery/

I would like to add a condition to test for null, but this looks kind of klunky:

 if (results == null) {
  return 0;
 } else {
  return results[1] || 0;
 }

Q: What's the elegant way to accomplish the above if/then statement?

Answer 1

return results == null ? 0 : ( results[1] || 0 );

Answer 2

if (typeof(results)!='undefined'){ 
    return results[1];
} else { 
    return 0; 
};

But you might want to check if results is an array. Arrays are of type Object so you will need this function

function typeOf(value) {
    var s = typeof value;
    if (s === 'object') {
        if (value) {
            if (value instanceof Array) {
                s = 'array';
            }
        } else {
            s = 'null';
        }
    }
    return s;
}

So your code becomes

if (typeOf(results)==='array'){
      return results[1];
}
else
{
      return 0;
}

Answer 3

return results == null ? 0 : (results[1] || 0);

Answer 4

return results==null ? 0 : ( results[1] || 0 );

Answer 5

you could try

if(typeof(results )=="undefined"){ return 0; } else { return results[1] || 0; }

Answer 6

the most terse solution would be to change return results[1] || 0; to return (results && results[1]) || 0.

Answer 7

return (results||0) && results[1] || 0;

The && operator acts as guard and returns the 0 if results if falsy and return the rightmost part if truthy.