TypeScript：ArrayLike接口缺少索引签名

Question

I tried to use TypeScript built-in interface, ArrayLike , but still got the error message like following:

Error:(12, 11) TS2420: Class 'Point' incorrectly implements interface 'ArrayLike'. Index signature is missing in type 'Point'.

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

class Point implements ArrayLike<number> {
    [0]: number = 10;
    length: number = 1;
}

How can I solve this problem? (or any workaround?)

Answer 1

How to implement the interface ArrayLike :

class Point implements ArrayLike<number> {
    [n: number]: number;
    length: number = 1;
    [0]: number = 10;
}

let p = new Point()
p[23] = 34; // ok
p[23] = "34"; // Error: Type 'string' is not assignable to type 'number'

Answer 2

If you want your Point to be an array then why not just extending the Array class?

class Point extends Array<number> {
    // add Point array methods here
}

This way Point will implement the ArrayLike<number> interface automatically.