In Typescript, is there any way to write a class as a Array, so I can do class[i], like a List in C#

Question

I'm a new game developer who started from C#.

Now I need to transfer one of my games to typescript.

I tried to customize a list in typescript which i'm very familiar to in C#. my code is like below:

export class List {

private items: Array;
constructor() {
    this.items = [];
}

get count(): number {
    return this.items.length;
}

add(value: T): void {
    this.items.push(value);
}

get(index: number): T {
    return this.items[index];
}
contains(item: T): boolean{
    if(this.items.indexOf(item) != -1){
        return true;
    }else{
        return false;
    }
}
clear(){
    this.items = [];
}
}

Still, I want to make like a array so I can do things like:

someList[i] = this.items[i];

I guess it's something like operator overload but I'm not quite sure.
Can any one tell me how to make it?
Thanks in advance.

Muhammed Albarmavi · Accepted Answer · 2018-08-10T10:16:02.347

2

Simply extend Array

export class List<T> extends Array<T> {

    constructor() {
        super();
    }

    get count(): number {
        return this.length;
    }

    add(value: T): void {
        this.push(value);
    }

    get(index: number): T {
        return this[index];
    }

    contains(item: T): boolean {
        if (this.indexOf(item) != -1) {
            return true;
        } else {
            return false;
        }
    }

    clear() {
        this.splice(0, this.count);
    }
}

edited Aug 10 '18 at 10:16

answered Aug 09 '18 at 03:48

Muhammed Albarmavi

23,240
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thanks for the quick reply, it works, except for the clear() method, it cant't be like this = []; – Evan Lyu Aug 09 '18 at 03:55
I'm pretty sure you don't need the `private items: Array` field anymore as that's handled by `Array` – rossipedia Aug 09 '18 at 04:00
but when i run the code to test like this: `let testList = new List();` `testList.add(1);` it log error : `TypeError: testList.add is not a function` – Evan Lyu Aug 09 '18 at 04:04
I have test and compiled to ES6 like this `tsc -target ES6` – Muhammed Albarmavi Aug 09 '18 at 04:24

score 1 · Answer 2 · answered Aug 09 '18 at 03:46

1

To achieve the effect of overloading the indexing operator, you would have to use a proxy to get the runtime behavior and then use an index signature for the typing, like this:

interface List<T> {
    [n: number]: T;
}

But proxies are serious machinery. You might be better off living with the boilerplate of method calls.

answered Aug 09 '18 at 03:46

Matt McCutchen

28,856
2
68
75

Thanks! think you are right, better get used to work with arrays – Evan Lyu Aug 09 '18 at 03:56
This way we can impliment IList interface ,wel done Matt – Muhammed Albarmavi Aug 09 '18 at 07:35

In Typescript, is there any way to write a class as a Array, so I can do class[i], like a List in C#

2 Answers2