How can I pass more parameters to a custom sort() function?

Question

I have an array of objects I need to sort on a custom function. Since I want to do this several times on several object attributes, I'd like to pass the key name for the attribute dynamically into the custom sort function:

function compareOnOneFixedKey(a, b) {
    a = parseInt(a.oneFixedKey)
    b = parseInt(b.oneFixedKey)
    if (a < b) return -1
    if (a > b) return 1
        return 0
}
    
arrayOfObjects.sort(compareByThisKey)

This should become something like:

function compareOnKey(key, a, b) {
    a = parseInt(a[key])
    b = parseInt(b[key])
    if (a < b) return -1
    if (a > b) return 1
        return 0
}
arrayOfObjects.sort(compareOn('myKey'))

Can this be done in a convenient way?

VisioN · Accepted Answer · 2013-01-24 00:11:18Z

17

You may add a wrapper:

function compareOnKey(key) {
    return function(a, b) {
        a = parseInt(a[key], 10);
        b = parseInt(b[key], 10);
        if (a < b) return -1;
        if (a > b) return 1;
        return 0;
    };
}

arrayOfObjects.sort(compareOnKey("myKey"));

answered Jan 24, 2013 at 0:11

VisioN

146k35 gold badges287 silver badges291 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Bergi · Accepted Answer · 2013-01-24 00:15:20Z

11

You would need to partially apply the function, e.g. using bind:

arrayOfObjects.sort(compareOn.bind(null, 'myKey'));

Or you just make compareOn return the actual sort function, parametrized with the arguments of the outer function (as demonstrated by the others).

answered Jan 24, 2013 at 0:15

Bergi

671k162 gold badges1k silver badges1.5k bronze badges

6 Comments

VisioN Over a year ago

Besides the method is good it still has compatibility problems.

Bergi Over a year ago

@VisioN: …but makes so many thing easier :-) For anybody considering supporting old IEs, the linked MDN page contains a shim

Paul S. Over a year ago

@VisioN .bind is supported in IE9 and this requires mimimal refactoring of current code

paolo.caminiti Over a year ago

On chrome, shim added, i cannot make this work function refacrtored as: function compareOn(a, b, key) { a = parseInt(a[key], 10) b = parseInt(b[key], 10) if (a < b) return -1 if (a > b) return 1 return 0 }

Bergi Over a year ago

@paolo: If you want to use partial application, the key argument needs to come first (as in your second snippet).

|

Paul S. · Accepted Answer · 2013-01-24 00:11:25Z

5

Yes, have the comparator returned from a generator which takes a param which is the key you want

function compareByProperty(key) {
    return function (a, b) {
        a = parseInt(a[key], 10);
        b = parseInt(b[key], 10);
        if (a < b) return -1;
        if (a > b) return 1;
        return 0;
    };
}
arrayOfObjects.sort(compareByProperty('myKey'));

compareByProperty('myKey') returns the function to do the comparing, which is then passed into .sort

answered Jan 24, 2013 at 0:11

Paul S.

66.6k9 gold badges130 silver badges143 bronze badges

1 Comment

paolo.caminiti Over a year ago

working well, but choosen the .bind() way for its flexibility. thank you for refactoring my code with the base 10 in parseInt :)

Nathan Morton · Accepted Answer · 2019-05-29 22:23:32Z

1

const objArr = [{
    name: 'Z',
    age: 0
  }, {
    name: 'A',
    age: 25
  }, {
    name: 'F',
    age: 5
}]
  
const sortKey = {
    name: 'name',
    age: 'age'
}

const sortArr = (arr, key) => {
    return arr.sort((a, b) => {
        return a[key] < b[key] ? -1 : a[key] > b[key] ? 1 : 0
    })
}
  
console.log("sortKey.name: ", sortArr(objArr, sortKey.name))
console.log("sortKey.age: ", sortArr(objArr, sortKey.age))

edited May 29, 2019 at 22:23

answered May 29, 2019 at 21:44

Nathan Morton

113 bronze badges

Collectives™ on Stack Overflow

How can I pass more parameters to a custom sort() function?

4 Answers 4

Comments

6 Comments

1 Comment

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

Comments

6 Comments

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related