Im trying to check if an array is defined while looping through another array
I've been beating my head on syntax options for awhile now.

here's what I got:

if(eval('self.dd_'+n.id+'[0][0]'))
      alert(msg)

This the code in context with function

function openform(id){
	//change button to 'save'
	obj.childNodes[b_pos].firstChild.value='save';
	
	//store values in array	
	var v=0; vArray=new Array(new Array(),new Array(),new Array());
	for (i=0; i < obj.childNodes.length; i++){
		n=obj.childNodes[i]
		if (n.id){
		 	vArray[0][v]=i;	
			vArray[1][v]=n.innerHTML; 
			vArray[2][v]=(n.innerText!=undefined?n.innerText:n.textContent)
			v++;			
		}
	}

	//write input boxes
	for (i=0; i < vArray[0].length; i++){
		n=obj.childNodes[vArray[0][i]];
		w=n.clientWidth;


//>>>>>>> BEGIN PROBLEM AREA <<<<<<<<<<

		if(eval('self.dd_'+n.id+'[0][0]'))
                      alert(msg)
		else 
                      alert("self.dd_"+n.id+"[0][0] is not defined")

		
//>>>>>>> END PROBLEM AREA <<<<<<<<<<

		inputwidth=(w>200?30:(w>50?8:1));
		n.innerHTML='<input name="'+n.id+'" size="'+inputwidth+'" value="'+vArray[2][i]+'">';
	}
}

this worked

if(window['dd_'+n.id])