Typescript - Sort generic array

Question

I'm trying to implement a function in typescript where the user can pass an array of objects and a property of one of the objects and return the list order by the property the user have chosen.

function OrderByArray(values: any[], orderType: any) { 
    //TODO: implement code
    return values;
}

Is any way to do it? I know how to sort an array but I don't know how to allow to send the typeof object and order by it.

Thanks!

Why you need to allow types as arguments? It's supposed to represent the sorted property? — martin
– martin, Commented Nov 6, 2016 at 15:54
The reason is because I'm working on a function where I have to receive an array and I don't know the object type and I have to return the values sorted by the object.property sent by the user. @Martin — gon250
– gon250, Commented Nov 6, 2016 at 15:57
So, how could I sort the user array[] by a string? I mean think about the user can send a person[], car[]... etc and ask to order by year, name, carbrand.. I don't know if you can get me. @Martin — gon250
– gon250, Commented Nov 6, 2016 at 16:07

Nitzan Tomer · Accepted Answer · 2017-10-18 12:59:45Z

14

You can use the Array.sort method:

function OrderByArray(values: any[], orderType: any) { 
    return values.sort((a, b) => {
        if (a[orderType] < b[orderType]) {
            return -1;
        }

        if (a[orderType] > b[orderType]) {
            return 1;
        }

        return 0
    });
}

I'm not sure what's the value of item[orderType], so you might need to change the ifs.

Edit

Using it:

let animals = [{ name: "cat" }, { name: "dog" }, { name: "lion" }];
let cars = [{ manufacturor: "ford" }, { manufacturor: "mazda" }, { manufacturor: "fiat" }];

console.log(OrderByArray(animals, "name").map(item => item.name)); // ["cat", "dog", "lion"]
console.log(OrderByArray(cars, "manufacturor").map(item => item.manufacturor)); // ["fiat", "ford", "mazda"]

(code in playground)

2nd Edit

In typescript 2.1 you'll be able to do:

function OrderByArray<T, K extends keyof T>(values: T[], orderType: K) {
    ...
}

More about keyof.

edited Oct 18, 2017 at 12:59

answered Nov 6, 2016 at 15:58

Nitzan Tomer

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6 Comments

gon250 Over a year ago

it could work, let me integrate it in my code, but not sure yet. thanks @nitzan-tomer

gon250 Over a year ago

in the first edit you did could be possible something like -> OrderByArray(values, orderType).map(item => item.orderType) ? @nitzan-tomer

Nitzan Tomer Over a year ago

If orderType is a variable then you need to do: OrderByArray(values, orderType).map(item => item[orderType])

gon250 Over a year ago

great! thanks! I'm pretty new using typescript. @nitzan-tomer

Nitzan Tomer Over a year ago

@chris.currin Fixed. It was a while ago, before the feature was actually out, maybe back then it was just keyof T, not sure or remember.

|

Ala A. · Accepted Answer · 2020-01-30 14:37:03Z

0

You probably do not need to return the results of values.sort(...) as mentioned in MDN

Array.sort actually changes, or mutates the array it sorts

edited Jan 30, 2020 at 14:37

Ala A.

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answered Jan 30, 2020 at 14:10

Developer

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