Question

我有json如下：

  "reviews":[
    {
    "notes": "Great place, perfect location but the best part was the Staff. Thank you so much for making our trip so wonderful!",
    "date": "2015-04-18",
    "rating":{"overall": 100}
    },
    {
    "notes": "I messed up the days I was supposed to be there but they did everything they could to get me a room, which I did. The guy at the front was super nice and then drew me an entire map based off of how much time I had there in Rome. It was extremely helpful and the restaurant he recommends (a friends who you get 10% off of) had good lasagna. Great place for a really reasonable price. Also, the doors do not automatically lock for you room, so just remember to lock your door when you leave. ",
    "date": "2016-04-18",
    "rating":{"overall": 94}
    }
    ]

我正在尝试获取最新日期（最近一次），以便我可以打印相关的＆＃34;笔记＆＃34;。

      function highestReview() {
        var maxNumb = [];
        for(var y = 0; y < data.reviews.length; y++){
          maxNumb.push(data.reviews[y].date);
        }
       var latestDate = new Date(Math.max.apply(null, maxNumb));
        console.log(latestDate);

      }
      highestReview();

我收到＆＃34;无效日期＆＃34;

Answer 1

根据docs，如果至少有一个参数无法转换为number，则结果为NaN 和new Date(NaN)将是 Invalid Date

在推入数组时将日期字符串换行到new Date。 DateObject通过Number后，将返回代表date的数字值。

＆＃13;

var data = {
  "reviews": [{
    "notes": "Great place, perfect location but the best part was the Staff. Thank you so much for making our trip so wonderful!",
    "date": "2015-04-18",
    "rating": {
      "overall": 100
    }
  }, {
    "notes": "I messed up the days I was supposed to be there but they did everything they could to get me a room, which I did. The guy at the front was super nice and then drew me an entire map based off of how much time I had there in Rome. It was extremely helpful and the restaurant he recommends (a friends who you get 10% off of) had good lasagna. Great place for a really reasonable price. Also, the doors do not automatically lock for you room, so just remember to lock your door when you leave. ",
    "date": "2016-04-18",
    "rating": {
      "overall": 94
    }
  }]
};

function highestReview() {
  var maxNumb = [];
  for (var y = 0; y < data.reviews.length; y++) {
    maxNumb.push(new Date(data.reviews[y].date));
  }
  var latestDate = new Date(Math.max.apply(null, maxNumb));
  console.log(latestDate);
}
highestReview();

＆＃13;

Answer 2

您可以使用Array#reduce并将日期作为字符串进行比较，而它是ISO date。

＆＃13;

var data = { "reviews": [{ "notes": "Great place, perfect location but the best part was the Staff. Thank you so much for making our trip so wonderful!", "date": "2015-04-18", "rating": { "overall": 100 } }, { "notes": "I messed up the days I was supposed to be there but they did everything they could to get me a room, which I did. The guy at the front was super nice and then drew me an entire map based off of how much time I had there in Rome. It was extremely helpful and the restaurant he recommends (a friends who you get 10% off of) had good lasagna. Great place for a really reasonable price. Also, the doors do not automatically lock for you room, so just remember to lock your door when you leave. ", "date": "2016-04-18", "rating": { "overall": 94 } }] },
    latestDate = data.reviews.reduce(function (r, a, i) {
        return !i || a.date > r ? a.date : r;
    }, undefined);
    
document.write('<pre>' + JSON.stringify(latestDate, 0, 4) + '</pre>');

＆＃13;

Answer 3

您必须先将日期值转换为Date对象：

function highestReview() {
        var maxNumb = [];
        for(var y = 0; y < data.reviews.length; y++){
          maxNumb.push(new Date(data.reviews[y].date));
        }
       var latestDate = new Date(Math.max.apply(null, maxNumb));
        console.log(latestDate);

      }
      highestReview();

希望有所帮助

从日期数组中返回最新日期

3 个答案: