从 JSON 获取最小和最大日期

Question

还有JSON：

[{"source":"2016-11-02","sourcecount":38},{"source":"2016-11-01","sourcecount":30},{"source":"2016-11-02","sourcecount":30},{"source":"2016-11-03","sourcecount":30}]

像在JavaScript中获取最大和最小日期一样吗？

Answer 1

var array = [{"source":"2016-11-02","sourcecount":38},{"source":"2016-11-01","sourcecount":30},{"source":"2016-11-02","sourcecount":30},{"source":"2016-11-03","sourcecount":30}];

var max = null;
var min = null;

for (var i = 0; i < array.length; i++) {
  var current = array[i];
  if (max === null || current.source > max.source) {
    max = current;
  }
  if (min === null || current.source < min.source) {
    min = current;
  }
}

document.getElementById('maxResult').innerHTML = max.source;
document.getElementById('minResult').innerHTML = min.source;

Max: <span id="maxResult"></span><br/ >
Min: <span id="minResult"></span>

Answer 2

只要您的日期格式是“yyyy-MM-dd”，您就可以这样做。

将日期字符串转换为 dateKey。随着日期的进行，它始终遵循升序。 20160101（1 月 1 日）总是小于 20161231（12 月 31 日）。

记住这一点，只需将日期转换为 dateKey 并将 dateKeys 映射到对象，然后提取 dateKeys 的最大值和最小值并返回实际日期。

var datesArray = [{
  "source": "2016-11-02",
  "sourcecount": 38
}, {
  "source": "2016-11-10",
  "sourcecount": 30
}, {
  "source": "2016-11-31",
  "sourcecount": 38
}, {
  "source": "2016-01-01",
  "sourcecount": 30
}];

var newObject = {};
var dates = datesArray.map(function(obj) {
  var regEx = new RegExp(/-/g);
  //Convert date to dateKey
  var dateKey = parseInt(obj.source.replace(regEx, ""), 10)
  newObject[dateKey] = obj;
  return dateKey;
});

console.log("Max", newObject[Math.max(...dates)].source);
console.log("Min", newObject[Math.min(...dates)].source);

Answer 3

好消息是，您的日期已经采用ISO 8601 格式。你可以简单地这样做，

var data = [{"source":"2016-11-02","sourcecount":38},{"source":"2016-11-01","sourcecount":30},{"source":"2016-11-02","sourcecount":30},{"source":"2016-11-03","sourcecount":30}];

var dateArr = data.map(function(v) {
  return new Date(v.source);
});

// Sort the date
dateArr.sort(function(a, b) {
  return a.getTime() - b.getTime();
  // OR `return a - b`
});

// The highest date is in the very last of array
var highestDate = dateArr[dateArr.length - 1];

// The lowest is in the very first..
var lowestDate = dateArr[0];

或者您更喜欢使用原始对象，那么您可以这样做，

var data = [{"source":"2016-11-02","sourcecount":38},{"source":"2016-11-01","sourcecount":30},{"source":"2016-11-02","sourcecount":30},{"source":"2016-11-03","sourcecount":30}];

data.sort(function(a,b) {
  var date1 = (new Date(a.source));
  var date2 = (new Date(b.source));
  return date1 - date2;
});

// highest date is '2016-11-03'
var highestDate = data[data.length - 1].source

// lowest date is '2016-11-01'
var lowestDate = data[0].source

Answer 4

试试这个

var data = [{"source":"2016-11-02","sourcecount":38},{"source":"2016-11-01","sourcecount":30},{"source":"2016-11-02","sourcecount":30},{"source":"2016-11-03","sourcecount":30}]
function compare(a,b) {
   if (new Date(a.source) < new Date(b.source))
     return -1;
   if (new Date(a.source) > new Date(b.source))
     return 1;
   return 0;
}
data = data.sort(compare);
var minDate = data[0].source;
var maxDate = data[data.length - 1].source;