Triangle numbers

<script language="javascript">        
var str = prompt('Input beginning number, ending number', '3,4'); 	   
var size = new Array(); 	  
 dimension = str.split(','); 	  
 var x = parseInt(dimension[0]);  	   
var y = parseInt(dimension[1]); 	  
 var z = 1; 	
for(i=0; i<x; i++) 	{ 	 		document.write(z+'&nbsp-&nbsp<br>'); 			z++ 			 		 		
for(j=0; j<y; j++) 		 			 			document.write(z+'&nbsp-&nbsp'); 
z =(z*(z+1)/2); 			 		 	} 
</script>

<script type="text/javascript">        
var str = prompt('Input beginning number, ending number', '3,4'); 	   
var size = new Array(); 	  
var dimension = str.split(','); 	  
var x = parseInt(dimension[0]);  	   
var y = parseInt(dimension[1]); 	  
var z = 0;
var max = 1;
for(i=0;i<y;i++) {
z++;
size.push((z*(z+1)/2));
}
for (iii=1;iii<y;iii++) {
max++;
for (ii=0;ii<max;ii++) {
document.write(size[ii]);
 if (ii<(max-1)) {
  document.write(" - ");
 }
}
document.write("<br/>");
}
</script>