CODEWITHSUNDEEP
javascriptjqueryarrayssortingecmascript-6
SilverSurfer
SilverSurfer

Reputation: 4366

How to sort an array by timestamp?

I am trying to sort this array by timestamp values. I want to sort them in ascending order and if any of them have an indefinite property, place it at the end. I currently have the error Cannot read property 'first_release_date' of undefined. How to solve this?

var array = 
[
  {
    "id": 1969,
    "cover": {
      "id": 1960,
      "url": "image.jpg"
    },
    "first_release_date": 1083542400,
    "name": "Item 1"
  },
  {
    "id": 113242,
    "name": "Item 2"
  },
  {
    "id": 25076,
    "first_release_date": 1540512000,
    "name": "Item 3"
  },
  {
    "id": 1969,
    "cover": {
      "id": 1960,
      "url": "image.jpg"
    },
    "name": "Item 4"
  },
  {
    "id": 9245,
    "first_release_date": 1292976000,
    "name": "Item 5"
  }
];

Object.keys(array).forEach((key) => {
  console.log(`Before: ${array[key].name}`)
});

array.sort((a,b) => a.array.first_release_date > b.array.first_release_date);

Object.keys(array).forEach((key) => {
  console.log(`After: ${array[key].name}`)
});

Upvotes: 1

Views: 852

Answers (1)

Shilly
Shilly

Reputation: 8589

You are almost there. Only need to provide a default value for when there's no date. Also, sort requires you to return a number, at the moment you return a boolean, which will be cast to 0 or 1. Which will break the sort for the cases you want to return a negative number.

var array = 
[
  {
    "id": 1969,
    "cover": {
      "id": 1960,
      "url": "image.jpg"
    },
    "first_release_date": 1083542400,
    "name": "Item 1"
  },
  {
    "id": 113242,
    "name": "Item 2"
  },
  {
    "id": 25076,
    "first_release_date": 1540512000,
    "name": "Item 3"
  },
  {
    "id": 1969,
    "cover": {
      "id": 1960,
      "url": "image.jpg"
    },
    "name": "Item 4"
  },
  {
    "id": 9245,
    "first_release_date": 1292976000,
    "name": "Item 5"
  }
];

Object.values(array).forEach((val) => {
  var d = new Date(val.first_release_date*1000).getFullYear();
  console.log(`Before: ${ val.name} ${d }`)
});

array.sort((a,b) => ( a.first_release_date || Number.POSITIVE_INFINITY ) - ( b.first_release_date || Number.POSITIVE_INFINITY ));

Object.values(array).forEach((val) => {
  var d = new Date(val.first_release_date*1000).getFullYear();
  console.log(`After: ${ val.name} ${d }`)
});

var reverse = JSON.parse( JSON.stringify( array ));

reverse.sort((a,b) => ( b.first_release_date || Number.NEGATIVE_INFINITY ) - ( a.first_release_date || Number.NEGATIVE_INFINITY ));

console.log( reverse );

Upvotes: 5

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