utility function to compare 2 arrays deeply

gistfile1.js

// utility function, returns true if arr1 is equal to arr2
function arrays_are_equivalent(arr1, arr2, ret) {
  if(ret === undefined) ret = true;
  if(arr1.length != arr2.length) return false;
  arr1.forEach(function(ele, i) {
    if(ele instanceof Array) {
      ret = ret && arrays_are_equivalent(ele, arr2[i]);
    }   
    else if(ele !== arr2[i]) {
      ret = false;
      return;
    }   
  }); 
  return ret;
}