getElementById has no properties

[irish]

How do I test if an object has properties? As you see below, I am iterating through a list of ids, in order to get the value of each. However in some instances, not all id elements will be on the page.
What I am looking for is something like 'hasproperties()' so that I could say:

 if (hasproperties( document.getElementById('GG_'+id))){
   other code...
}

I am currently getting a js error if the getElementById('GG_'+id) is not on found on the page.

var ids = document.getElementById('ggids').value;
	var tmp = ids.split(',');
	
	for(i=0;i<tmp.length;i++){
		var id = tmp[i];
		
		var qty = document.getElementById('GG_'+id).value;
other code...

	}

[tech_support]

You can use try { //do stuff here } catch(ex) {}

[Trinithis]

You need to check for the object's existence before checking for existence of any properties.

var o;
if(o=document.getElementById("foobar") && hasProperties(o)) {
   //do something
   }

or

var o = document.getElementById("foobar");
if(o && hasProperties(o)) {
   //do something
   }

(Different ways of doing the same thing.)

[codeexploiter]

Make sure that the code that access element by its ID only after its loading.