从json获得最新纪录，有纪录时间

Question

我正在使用angularjs.创建应用程序。我有json喜欢：

{
    "dps": {
      "1455719820": 0,
      "1455720150": 0,
      "1455720480": 0,
      "1455720810": 0,
      "1455721140": 0,
      "1455721470": 0,
      "1455721800": 0,
      "1455722130": 0
    }
  }

我想从json获得最近时间的价值。我不知道怎么办。

Answer 1

在我看来，最兼容的方式和最容易阅读：

1. 使用Object.keys
2. sort()如有必要（在您的示例中没有必要）
3. 使用pop或arr [arr.length-1]
访问该值（在您的示例中始终为0）

var o = {
    "dps": {
      "1455719820": 10,
      "1455720150": 90,
      "1455720480": 110,
      "1455720810": 560,
      "1455721140": 670,
      "1455721470": 120,
      "1455721800": 9,
      "1455722130": 130
    }
  }

// just sorting
var arr = Object.keys(o.dps).sort(); // your keys were actually already sorted
console.log(arr);

// To get the latest value; 
var newest = arr.pop();
var val = o.dps[newest];
console.log(newest,val)

Answer 2

 var biggest=0;
 var obj = {
    "dps": {
      "1455719820": 0,
      "1455720150": 0,
      "1455720480": 0,
      "1455720810": 0,
      "1455721140": 0,
      "1455721470": 0,
      "1455721800": 0,
      "1455722130": 0
    }
  }
for(key in obj.dps){
    if(biggest<key){
          biggest = key;
    }
}

// biggest will now have the biggest timestamp 

Answer 3

您可以使用Array#reduce执行单个循环，而无需事先对键进行排序。

SELECT table1.id
FROM table1
LEFT JOIN table2
ON table1.id = table2.requestID
WHERE table1.username <> 'user 2'
and ( table2.username <> 'user 2' OR table2.username IS NULL )

Answer 4

var o = {
  "dps": {
    "1455719820": 0,
    "1455720150": 0,
    "1455720480": 0,
    "1455720810": 0,
    "1455721140": 0,
    "1455721470": 0,
    "1455721800": 0,
    "1455722130": 0
  }
}

var max = Math.max.apply(Math, Object.keys(o.dps));

console.log(max);