ajax请求之返回数据的顺序问题分析

$a = array( '-1'=> 10 ,'-3' => 2, '0' => '5' ,'-2' => 4);

$a = array('-3' => 2, '-2' => 4，'0' => '5', '-1'=> 10  );

$i = 0;
foreach ($data as $k => $v) {
   $tmp[$i]['data'] = $v;
   $tmp[$i]['key'] = $k;
   $i++;
}

{
  "rows": [
    {
      "data": "2",
      "key": 0-3
    },
    {
      "data": "4",
      "key": -12
    },
    {
      "data": "5",
      "key": 0
    },
    {
      "data": "10",
      "key": -1
    }
  ]
}