Sort array of object javascript by attribute

Question

I have an unsorted array of object having 2 revelant property: type , and date . I need to sort this array:

1. By date and
2. By type (for every year, deposit should go first before withdrawal )

Here is an example of input:

let i = [
    {
        date:'2017',
        type:'withdrawal',
        amount:-5
    },
    {
        date:'2016',
        type:'deposit',
        amount:12
    },
    {
        date:'2018',
        type:'deposit',
        amount:54
    },
    {
        date:'2017',
        type:'deposit',
        amount:20
    },
    {
        date:'2016',
        type:'withdrawal',
        amount:55
    },
    {
        date:'2018',
        type:'withdrawal',
        amount:54
    }
]  

The goal is to output something like this:

let o = [
    {
        date:'2016',
        type:'deposit',
        amount:12
    },
    {
        date:'2016',
        type:'withdrawal',
        amount:55
    },
    {
        date:'2017',
        type:'deposit',
        amount:20
    },
    {
        date:'2017',
        type:'withdrawal',
        amount:-5
    },
    {
        date:'2018',
        type:'deposit',
        amount:54
    },
    {
        date:'2018',
        type:'withdrawal',
        amount:54
    }
]

So far I managed to sort the array by date using:

o = i.sort((a,b)=>(a.date - b.date))

But I can't find a way to sort it by type

Answer 1

You can use "sort" like below. By using "localeCompare" it will sort "type" in increasing order - which is "deposit" will come before "withdrawl" as "d" comes before "w"

That is use this -

i.sort((a,b) => ((+a.date) - (+b.date) || (a.type.localeCompare(b.type))))

• you sort first by "date" and if dates are same then it goes in OR condition (as a.date - b.date will be 0) to check "type"

 let i = [ { date:'2017', type:'withdrawal', amount:-5 }, { date:'2016', type:'deposit', amount:12 }, { date:'2018', type:'deposit', amount:54 }, { date:'2017', type:'deposit', amount:20 }, { date:'2016', type:'withdrawal', amount:55 }, { date:'2018', type:'withdrawal', amount:54 } ] i.sort((a,b) => ((+a.date) - (+b.date) || (a.type.localeCompare(b.type)))) console.log(i) 

Answer 2

You can use string#localCompare to sort the array first based on date and then on type .

 let arr = [ { date:'2017', type:'withdrawal', amount:-5 }, { date:'2016', type:'deposit', amount:12 }, { date:'2018', type:'deposit', amount:54 }, { date:'2017', type:'deposit', amount:20 }, { date:'2016', type:'withdrawal', amount:55 }, { date:'2018',type:'withdrawal', amount:54 } ]; arr.sort((a,b) => a.date.localeCompare(b.date) || a.type.localeCompare(b.type)); console.log(arr); 

Answer 3

While probably not the most optimal solution, I concat'ed the type onto the date as a string for both "a" and "b" in the Array.prototype.sort method, and sorted the array based on that.

i.sort((a,b) => {
  let aStr = `${a.date}${a.type}`;
  let bStr = `${b.date}${b.type}`;
  if(aStr > bStr) {
    return 1;
  } else if(aStr === bStr) {
    return 0;
  } else {
    return -1;
  }
});

Hope that helps!