JavaScript sort an array of objects based array of properties

Question

I have for example this dataset:

const order = [
  { key: "job", direction: "ascending" },
  { key: "age", direction: "descending" },
];

const records = [
  { name: "christian", age: 40, job: "developer" },
  { name: "andrew", age: 48, job: "developer" },
  { name: "elisabeth", age: 31, job: "floor manager" },
  { name: "oscar", age: 61, job: "floor manager" },
  { name: "gisela", age: 51, job: "area manager" },
  { name: "buffy", age: 27, job: "trainee" },
  { name: "carl", age: 23, job: "trainee" },
];

I need to sort the records array according to the criteria from order array. I ended up with this solution:

const sorted = records.sort(
  (recordA, recordB) =>
    recordA.job.localeCompare(recordB.job) || recordA.age - recordB.age
);

But I cant understand how can I use the order array instead of hardcoded the job and age properties. The order array can have many properties.

so you need two array one is sorted on the basis of job(ascending) and another one which is sorted on the basis of age(descending) — Vibhav
– Vibhav, Commented Mar 22, 2021 at 15:01
It’d be a lot easier if the order array also contained an entry that tells you if the property is to be sorted numerically or lexicographically, at least if you want to keep using localCompare and -. Alternatively, everything can be generalized with (a[key] < b[key] ? -1 : a[key] > b[key] ? 1 : 0). — Sebastian Simon
– Sebastian Simon, Commented Mar 22, 2021 at 15:01
I would look at this question and its answers for inspiration. — Heretic Monkey
– Heretic Monkey, Commented Mar 22, 2021 at 15:05

Nina Scholz · Accepted Answer · 2021-03-22 15:05:36Z

You could take a closure over the wanted order and check the value if finite then return the delta or treat the values as string.

Inside sorting function iterate as long as the return value is falsy and take this value as return value for sorting.

const
    sortBy = order => (a, b) => {
        let r;
        order.some(({ key, direction }) => r = (isFinite(a[key]) && isFinite(b[key])
            ? a[key] - b[key]
            : a[key].toString().localeCompare(b[key])        
        ) * (direction === 'ascending' || -1))
        return r;
    },
    records = [{ name: "christian", age: 40, job: "developer" }, { name: "andrew", age: 48, job: "developer" }, { name: "elisabeth", age: 31, job: "floor manager" }, { name: "oscar", age: 61, job: "floor manager" }, { name: "gisela", age: 51, job: "area manager" }, { name: "buffy", age: 27, job: "trainee" }, { name: "carl", age: 23, job: "trainee" }],
    order = [{ key: "job", direction: "ascending" }, { key: "age", direction: "descending" }];

console.log(records.sort(sortBy(order)));

.as-console-wrapper { max-height: 100% !important; top: 0; }

trincot · Accepted Answer · 2021-03-22 15:08:32Z

3

Just loop over the order data and make the comparisons:

let order = [{ key: "job", direction: "ascending" }, { key: "age", direction: "descending" }];
let records = [{ name: "christian", age: 40, job: "developer" }, { name: "andrew", age: 48, job: "developer" }, { name: "elisabeth", age: 31, job: "floor manager" }, { name: "oscar", age: 61, job: "floor manager" }, { name: "gisela", age: 51, job: "area manager" }, { name: "buffy", age: 27, job: "trainee" }, { name: "carl", age: 23, job: "trainee" }];

records.sort(function (a, b) {
    for (let {key, direction} of order) {
        if (a[key] !== b[key]) return (direction[0] === "a") === (a[key] < b[key]) ? -1 : 1;
    }
    return 0;
});

console.log(records);

.as-console-wrapper { max-height: 100% !important; top: 0; }

answered Mar 22, 2021 at 15:08

trincot

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2 Comments

Jonas Wilms Over a year ago

direction[0] === "a" you're going to win the code golf :)

trincot Over a year ago

Then I would have left out one = or even direction<"b" ;-)

Jonas Wilms · Accepted Answer · 2021-03-22 15:07:17Z

You could use (a[key] > b[key]) - (a[key] < b[key]) to compare two values either lexically or numerically (if both are numbers). This could then be used like:

const order = [
  { key: "job", direction: "ascending" },
  { key: "age", direction: "descending" },
];

const records = [
  { name: "christian", age: 40, job: "developer" },
  { name: "andrew", age: 48, job: "developer" },
  { name: "elisabeth", age: 31, job: "floor manager" },
  { name: "oscar", age: 61, job: "floor manager" },
  { name: "gisela", age: 51, job: "area manager" },
  { name: "buffy", age: 27, job: "trainee" },
  { name: "carl", age: 23, job: "trainee" },
];

const compare = (key) => (a, b) => (a[key] > b[key]) - (a[key] < b[key]);
const or = (a, b) => (...v) => a(...v) || b(...v);
 
const sorter = order.map(it => compare(it.key)).reduce(or);
const sorted = records.sort(sorter);
console.log(sorted);

_{The implementation of direction was left to the reader}

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