arrayList

class ArrayList {
	size = 0;
	elementData = new Array(100);
	constructor() {}

	add(element) {
		this.elementData[this.size++] = element;
		return true;
	}
	addIndex(index, element) {
		for (let i = this.size - 1; i >= index; i--) {
			this.elementData[i + 1] = this.elementData[i];
		}
		this.elementData[index] = element;
		this.size++;
		return true;
	}
	remove(index) {
		const removed = this.elementData[index];
		for (let i = index + 1; i <= this.size - 1; i++) {
			this.elementData[i - 1] = this.elementData[i];
		}
		this.size--;
		this.elementData[this.size] = null;
		return removed;
	}
	get(index) {
		return this.elementData[index];
	}
	getSize() {
		return this.size;
	}
	indexOf(o) {
		for (let i = 0; i < this.size; i++) {
			if (o === this.elementData[i]) {
				return i;
			}
		}
		return -1;
	}
	toString() {
		let str = '[';
		for (let i = 0; i < this.size; i++) {
			str += this.elementData[i];
			if (i < this.size - 1) str += ',';
		}
		return str + ']';
	}
	iterator() {
		let cursor = 0;
		return {
			hasNext: () => {
				return this.size != cursor;
			},
			next: () => {
				const done = cursor >= this.size;
				const value = !done ? this.elementData[cursor++] : undefined;
				return {
					done: cursor === this.size;,
					value: value,
				};
			},
		};
	}
}

const numbers = new ArrayList();

numbers.add(10);
numbers.add(20);
numbers.add(30);
numbers.add(40);
console.log('add', numbers.toString());
numbers.addIndex(1, 50);
console.log('addIndex', numbers.toString());
numbers.remove(2);
console.log('remove', numbers.toString());
console.log('get', numbers.get(2));
console.log('size', numbers.getSize());
console.log('indexof', numbers.indexOf(30));
console.log('loop start');
for (let i = 0; i < numbers.getSize(); i++) {
	console.log(numbers.get(i));
}
console.log('loop end');
console.log('iterator start');
const it = numbers.iterator();
while (it.hasNext()) {
	let value = it.next();
	console.log(value);
}
console.log('iterator end');
console.log(numbers.toString());