Reimplement javascript arrays. You can not use an array internally to hold data.

ArrayLike.ts

class ArrayLike<T> implements Iterable<T> {
    private _values: Record<number, T> = {};
    private _size: number;
    
    constructor(...values: T[]) {
        this._values = {};
        this._size = 0;
        values.forEach(val => this.add(val));
    }
    
    add(val: T): void {
        this._values[this._size] = val;
        this._size++;
    }
    
    remove(): void {
        if (this._size > 0) {
            delete this._values[this._size - 1];
            this._size--;
        }
    }

    get(): T {
        if (this._size > 0) {
            return this._values[this._size - 1];
        }
        return null;
    }
    
    getAt(index: number): T {
        if (index < 0 || index >= this._size) {
            return null;
        }
        return this._values[index];
    }
    
    setAt(index: number, val: T): void {
        if (index < 0 || index >= this._size) {
            return;
        }
        this._values[index] = val;
    }
    
    size(): number {
        return this._size;
    }
    
    isEmpty(): boolean {
        return this._size === 0;
    }
    
    clear(): void {
        Object.keys(this._values).forEach(key => {
            delete this._values[key];
        });
        this._size = 0;
    }

    [Symbol.iterator]() {
        const size = this._size;
        const values = Object.values(this._values);
        let index = 0;
        return {
            next(): IteratorResult<T> {
                if (index < size) {
                    const value = values[index];
                    index++;
                    return {
                        value,
                        done: false
                    };
                }
                return {
                    value: undefined,
                    done: true
                };
            }
        };
    }
    
    toString(): string {
        return `[${Object.values(this._values).map(val => val.toString()).join(', ')}]`;
    }
}

const values = new ArrayLike<number>(1, 5, 10, 20, 50, 100, 200);

for (const val of values) {
    console.log(val);
}