獲得最近從具有劃時代的時間

Question

我使用angularjs.I創建應用JSON記錄有JSON，如：

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

我想從json的最近時間的價值。我不知道我該怎麼做。

Answer 1

最兼容的方式，最簡單的在我看來閱讀：

1. 使用Object.keys
2. sort()他們，如果有必要（在你的例子不是必要的）
3. 訪問值（在你的榜樣永遠0）使用POP或ARR [arr.length-1]

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

你可以使用Array#reduce，執行單迴路，不需事先排序鍵。

var data = { "dps": { "1455719820": 0, "1455720150": 0, "1455720480": 0, "1455720810": 0, "1455721140": 0, "1455721470": 0, "1455721800": 0, "1455722130": 42 } }, 
 
    result = data.dps[Object.keys(data.dps).reduce(function (r, a) { 
 
     return r < a ? a : r; 
 
    }, 0)]; 
 

 
console.log(result);

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);