javascript array optimization -

i have multiple array items nested inside each other , cashed data want call, want know if there way can following. want reduce total number of variables.

 //function check change     function datachange(olddata, newdata){    if(olddata > newdata){       alert('change');      }    }   //current code     var num1 = item[key]['b02'][0];  var num2 = item[key]['b02'][1];  var numold1 = itemold[key]['b02'][0];  var numold2 = itemold[key]['b02'][1];   datachange(num1,numold1);   //proposed code  var num1 = ['b02'][0];  var num2 = ['b02'][1];  datachange(item[key].num1, itemold[key].num1); 

you don't need variables @ other item, itemold, , key:

datachange(item[key]['b02'][0], itemold[key]['b02'][0]); 

which can written

datachange(item[key].b02[0], itemold[key].b02[0]); 

but since item[key]['b02'] , item[key]['b02'] objects, can use variables refer them , use [0] , [1]:

var current = item[key]['b02']; var old = itemold[key]['b02'];  datachange(current[0], old[0]);