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How to sort an array of objects by date in JavaScript?

If you want to sort an array of objects, call the sort() method and pass a comparison function to it. Inside the comparison function, access that property of an object whose value is of type Date. Then call the getTime() method to get the milliseconds version of the date. After that, return 1 when the first argument is greater than the second and return -1 when the first argument is less than the second.

Let's understand the entire process of sorting an array of objects with the help of an example:

Suppose you have an inventory of products, and each product is stored as an object. If you want to sort this inventory by date, then execute the following code:

let inventory = [
  {
    name: 'Green Floral Midi Dress',
    id: 823,
    price: '$45',
    fabric: 'Polyester',
    dateOfAdding: new Date(2022, 2, 10)
  },
  {
    name: 'Blue Ripped Jeans',
    id: 743,
    price: '$29.99',
    type: 'High Waist',
    dateOfAdding: new Date(2021, 11, 25)
  },
  {
    name: 'Pink Satin Sleveless Dress',
    id: 803,
    price: '$33',
    fabric: 'Polyester',
    dateOfAdding: new Date(2022, 1, 27)
  }
];

inventory.sort((a, b)=>{
  if(a.dateOfAdding.getTime() > b.dateOfAdding.getTime()){
    return 1;
  }else if(a.dateOfAdding.getTime() < b.dateOfAdding.getTime()){
    return -1
  }else{
    return 0;
  }
});
console.log(inventory);

Output

[{
  name: "Blue Ripped Jeans",
  id: 743,
  price: "$29.99",
  type: "High Waist",
  dateOfAdding: Sat Dec 25 2021
},
{
  name: "Pink Satin Sleveless Dress",
  id: 803,
  price: "$33",
  fabric: "Polyester",
  dateOfAdding: Sun Feb 27 2022
},
{
  name: "Green Floral Midi Dress",
  id: 823,
  price: "$45",
  fabric: "Polyester",
  dateOfAdding: Thu Mar 10 2022
}]

Here is the explanation of the code:

1. The products are stored as an array of objects.

let inventory = [
  {
    name: 'Green Floral Midi Dress',
    id: 823,
    price: '$45',
    fabric: 'Polyester',
    dateOfAdding: new Date(2022, 2, 10)
  },
  {
    name: 'Blue Ripped Jeans',
    id: 743,
    price: '$29.99',
    type: 'High Waist',
    dateOfAdding: new Date(2021, 11, 25)
  },
  {
    name: 'Pink Satin Sleveless Dress',
    id: 803,
    price: '$33',
    fabric: 'Polyester',
    dateOfAdding: new Date(2022, 1, 27)
  }
];

2. Since we want to sort the array by date, we must pass the comparison function to the sort() method. There is a set of rules that you must adhere to if you want to sort using the comparison function:

a. If you want to sort in ascending order, then return 1 when the first argument is greater than the second argument and return -1 when the first argument is less than the second argument.

arr.sort((a, b) => {
  if(a > b){
    return 1;
  }else if(a < b){
    return -1;
  }else{
    return 0;
  }
});

b. On the other hand, if you want to sort in descending order, then return -1 when the first argument is greater than the second one and return 1 when the first argument is less than the second one.

arr.sort((a, b) => {
  if(a > b){
    return -1;
  }else if(a < b){
    return 1;
  }else{
    return 0;
  }
});