var arr = new Array(["b", 2, "a", 4],["c",3,"d",6]);
arr.forEach(function(item){
  alert(item); //b, 2, a, 4和c,3,d,6
});

var arr = new Array(["b", 2, "a", 4],["c",3,"d",6]);
arr.forEach(function(item, i){
  alert(item+"-"+i); //b, 2, a, 4-1和c,3,d,6-2;
  item.forEach(function(items, j){
    alert(items+"---------"+j); //b------0;2-------1;a----2;4------3;  c-----0;3-----1;d----2;6----3
  });
});

var arr = new Array(["b", 2, "a", 4],["c",3,"d",6]);
$.each(arr, function(item){
  alert(item); //0;1
});

var arr = new Array(["b", 2, "a", 4],["c",3,"d",6]);
$.each(arr, function(i, item){
  alert(item+"-"+i); //b, 2, a, 4-1和c,3,d,6-2;
  $.each(item, function(j, items){
    alert(items+"---------"+j); //b------0;2-------1;a----2;4------3;  c-----0;3-----1;d----2;6----3
  });
});