Implement ArrayList with Typescript

The complete code

class ArrayList<E> {

  /** * The number of elements */
  private sizeNum:number = 0;

  /** * all elements */
  private elements:E[] = [];

  private static readonly DEFAULT_CAPACITY = 10;
  private static readonly ELEMENT_NOT_FOUND = -1;
  
  constructor(capaticy? :number) {
    capaticy = (capaticy < ArrayList.DEFAULT_CAPACITY) ? ArrayList.DEFAULT_CAPACITY : capaticy;
    this.elements = new Array<E>(capaticy);
  }

  /** * clears all elements */
  public clear() {
    for (let i = 0; i < this.sizeNum; i++) {
      this.elements[i] = null;
    }
    this.sizeNum = 0;
  }

  /** * gets the number of elements *@return* /
  public size():number {
    return this.sizeNum;
  }

  /** * check whether the value is null *@return* /
  public isEmpty():boolean {
    return this.sizeNum === 0;
  }

  /** * Whether to contain an element *@return* /
  public contains(element:E):boolean {
    return this.indexOf(element) ! = ArrayList.ELEMENT_NOT_FOUND; }/** * add the element to the end *@param element* /
  public add(element:E) {
    this.addToIndex(this.sizeNum, element);
  }

  /** * gets the element * at index position@param index* /
  public get(index:number):E {
    this.rangeCheck(index);
    return this.elements[index];
  }

  /** * Sets the element * at index position@param index
   * @param element* /
  public set(index:number.element:E):E {
    this.rangeCheck(index);
    const old:E = this.elements[index];
    this.elements[index] = element;
    return old;
  }

  /** * inserts an element * at index position@param index
   * @param element* /
  public addToIndex(index:number, element:E) {
    this.rangeCheckAdd(index);

    this.ensureCapacity(index + 1);

    for (let i = this.sizeNum - 1; i > index; i--) {
      this.elements[i] = this.elements[i - 1];
    }
    this.elements[index] = element;
    this.sizeNum++;
  }

  /** * delete element * at index position@param index* /
  public remove(index:number):E {
    this.rangeCheck(index);
    const oldElement:E = this.elements[index];
    for (let i = this.sizeNum; i > index; i--) {
      this.elements[i] = this.elements[i - 1];
    }
    this.sizeNum--;
    return oldElement;
  }

  /** * View the index of the element *@param element* /
  public indexOf(element:E):number {
    return ArrayList.ELEMENT_NOT_FOUND;
  }

  private outOfBounds(index:number) {
    throw new Error(`ArrayIndexOutOfBoundsException: ${index}`);
  }

  private rangeCheck(index:number) {
    if (index < 0 || index >= this.sizeNum) {
      this.outOfBounds(index); }}private rangeCheckAdd(index:number) {
    if (index < 0 || index > this.sizeNum) {
      this.outOfBounds(index); }}/** * ensure that there is a capacity **@param capacity* /
  public ensureCapacity(capacity:number) {
    const oldCapacity = this.elements.length;
    if (oldCapacity > capacity) return;

    const newCapacity = oldCapacity + (oldCapacity >> 1);
    const newElements:E[] = new Array<E>(newCapacity);
    for (let i = 0; i< this.sizeNum; i++) {
      newElements[i] = this.elements[i];
    }
    this.elements = newElements;
  }

  public toString():string {
    let str:string = ' ';
    str += `size=The ${this.sizeNum}[`;
    for (let i = 0; i < this.sizeNum; i++) {
      if(i ! = =0) {
        str += ', ';
      }
      str += this.elements[i];
    }
    str += '] '
    returnstr; }}export default ArrayList;
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