Javascript如果键重复，则替换项目，并排序和删除最后2个项目以外的项目 [英] Javascript Replace item if key is duplicate and sort and delete except last 2 items

问题描述

我有如下数组，我想按键对它进行排序，然后删除除最后2个项目以外的所有内容，然后删除其余的项目。

I have array like below , I want to sort it by key and then remove everything except last 2 items and delete remaining.

var status = new Array();
status.push({key: 'BOB', value: 10});
status.push({key: 'TOM', value: 3});
status.push({key: 'ROB', value: 22});
status.push({key: 'JON', value: 7});

例如，如果我再次用重复的键在下面按下：

If I again push below with duplicate key for example :

status.push({key: 'BOB', value: 20});

我需要以下输出，如何在javascript中实现呢？

I need following output , how do i achieve this in javascript.

[
  {
    "key": "BOB",
    "value": 20
  },
  {
    "key": "TOM",
    "value": 3
  },
  {
    "key": "ROB",
    "value": 22
  },
  {
    "key": "JON",
    "value": 7
  }
]

注意：我稍后需要按键对它进行排序。

Note : I need to sort this by key later.

编辑：如果我有这样的对象，如何按键排序？

Edit : If I have object like this , How do i sort by keys ? and get only last 2 items and delete remaining.

var status = new Object();
status['BOB'] = 10
status['TOM'] = 3
status['ROB'] = 22
status['JON'] = 7

推荐答案

使用对象代替使用数组：

Instead of using an array, use an object:

(function () {
  var status = {};
  status['BOB'] = 10;
  status['TOM'] = 3;
  status['ROB'] = 22;
  status['JON'] = 7;
  status['BOB'] = 20;
  // convert to array
  var output = Object.keys(status)
    // sort by key
    .sort()
    // keep last two after sorting
    .slice(-2)
    // convert [key, value] to { key, value }
    .map(function (key) {
      return { key: key, value: status[key] };
    });

  console.log(output);
})();

.as-console-wrapper{max-height:100%!important}

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