extending the array class

superArray.ts

export class SuperArray<Data> extends Array {
    static from<Data>(input: Data[]): SuperArray<Data> {
        return new SuperArray(input);
    }

    constructor(input: any[]) {
        super(input.length);
        input.forEach((element, index) => {
            this[index] = element;
        })
    }

    toArray(): Data[] {
        return [...this];
    }

    map(...args): SuperArray<Data> {
        return new SuperArray(super.map(args));
    }

    filter(...args): SuperArray<Data> {
        return new SuperArray(super.filter(args));
    }
    
    split(comparator: (previous: Data, current: Data) => boolean): Data[][] {
        return this.reduce((acc, next, index) => {
            if(acc.length === 0) {
                acc.push([next])
                return acc
            }
            
            const previous = acc[acc.length - 1]
            if(comparator(previous, next)){ 
                acc.push([next])
            } 
            else {
                previous.push(next)
            }
            return acc
        },[])
    }

    at(index): Data {

        if (index < 0) {
            const reverseIndex = this.length - index;                
            return reverseIndex >= 0 ? this[reverseIndex] : undefined;
        }
        return this.length > index ? this[index] : undefined;
    }
}