How to sort an array from an object?

Question

How to sort an array from an object ? The code :

         let A = [ { text: '故事', value: 'story', },
                   { text: '诗歌', value: 'poetry', },
                   { text: '励志', value: 'inspirational', }
                 ];
         // array B from backend** 
         let B = { 
                   story: 2,
                   poetry: 34,
                   inspirational: 30,
                 };

I want to get this :

             [ 
               { text: '诗歌', value: 'poetry', },
               { text: '励志', value: 'inspirational'},
               { text: '故事', value: 'story', }, 
             ];

So you're trying to sort from greatest to smallest based on the value of a property of an object you get? — Andrew Li
– Andrew Li, Commented Jul 26, 2018 at 3:11
A.sort((a, b) => B[b.value] - B[a.value]) for greatest to smallest — Andrew Li
– Andrew Li, Commented Jul 26, 2018 at 3:14

NullPointer · Accepted Answer · 2018-07-26 03:27:22Z

3

Simply you can use JavaScript sort function.

Note: When sorting numbers, you can simply use the compact comparison:

Compact Comparison:: myArray.sort((n1,n2) => n1 - n2);

let A = [ { text: '故事', value: 'story', },
                   { text: '诗歌', value: 'poetry', },
                   { text: '励志', value: 'inspirational', }
                 ];
         // array B from backend** 
         let B = { 
                   story: 2,
                   poetry: 34,
                   inspirational: 30,
                 };
 A.sort((a, b) => B[b.value]-B[a.value] );
                 console.log(A);

edited Jul 26, 2018 at 3:27

answered Jul 26, 2018 at 3:16

NullPointer

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Comments

ggorlen · Accepted Answer · 2018-07-26 03:17:49Z

You can use an arrow function in array.sort as a custom comparator. Sorting in reverse order is accomplished by indexing into the B object to retrieve the sort value for compared elements and subtracting a's value from b.

let A = [ 
  { text: '故事', value: 'story', },
  { text: '诗歌', value: 'poetry', },
  { text: '励志', value: 'inspirational', }
];
let B = { 
  story: 2,
  poetry: 34,
  inspirational: 30,
};

const sorted = A.sort((a, b) => B[b.value] - B[a.value]);

console.log(sorted);

Eddie · Accepted Answer · 2018-07-26 03:17:52Z

You can use sort() to arrange the array elements. You can use Number.NEGATIVE_INFINITY as a default value if the value does not exist on B. This will put the undefined value last.

let A = [{"text":"诗歌","value":"poetry"},{"text":"励志","value":"inspirational"},{"text":"故事","value":"story"}];
let B = {"story":2,"poetry":34,"inspirational":30};

A.sort((x, y) => (B[y.value] || Number.NEGATIVE_INFINITY) - (B[x.value] || Number.NEGATIVE_INFINITY));

console.log(A);

Sheshank S. · Accepted Answer · 2018-07-26 03:17:56Z

1

Try this, it uses an arrow function and array.sort:

let A = [{
    text: '故事',
    value: 'story',
  },
  {
    text: '诗歌',
    value: 'poetry',
  },
  {
    text: '励志',
    value: 'inspirational',
  }
];
// array B from backend** 
let B = {
  story: 2,
  poetry: 34,
  inspirational: 30,
};
A.sort((a, b) => B[b.value] - B[a.value]);
console.log(A);

answered Jul 26, 2018 at 3:17

Sheshank S.

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Comments

Ele · Accepted Answer · 2018-07-26 03:33:49Z

Using the function Array.prototype.sort you can accomplish your desired output.

This B[bV] - B[aV] will return a value lesser than 0 or greater than 0 or equal to 0 which is what the function sort is expecting on to locate the elements at the specific index according to their value from object B.

let A = [{    text: '故事',    value: 'story',  },  {    text: '诗歌',  value: 'poetry',  },  {    text: '励志',    value: 'inspirational',  }],
    B = {  story: 2,  poetry: 34,  inspirational: 30};
A.sort(({value: aV}, {value: bV}) => B[bV] - B[aV]);

console.log(A);

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