How the object "this.head" is updated without assignement?

class Node {
  constructor(val) {
    this.val = val;
    this.next = null;
  }
}

class SinglyLinkedList {
  constructor() {
    this.head = null;
    this.tail = null;
    this.length = 0;
  }
  push(val) {
    var newNode = new Node(val);
    if (!this.head) {
      this.head = newNode;
      this.tail = this.head;
    } else {
      this.tail.next = newNode;
      this.tail = newNode;
    }
    this.length++;
    return this;
  }
  pop() {
    if (!this.head) return undefined;
    var current = this.head;
    var newTail = current;
    while (current.next) {
      newTail = current;
      current = current.next;
    }
    this.tail = newTail;
    this.tail.next = null;
    this.length--;
    if (this.length === 0) {
      this.head = null;
      this.tail = null;
    }
    return current;
  }
  shift() {
    if (!this.head) return undefined;
    var currentHead = this.head;
    this.head = currentHead.next;
    this.length--;
    if (this.length === 0) {
      this.tail = null;
    }
    return currentHead;
  }
  unshift(val) {
    var newNode = new Node(val);
    if (!this.head) {
      this.head = newNode;
      this.tail = this.head;
    }
    newNode.next = this.head;
    this.head = newNode;
    this.length++;
    return this;
  }
  get(index) {
    if (index < 0 || index >= this.length) return null;
    var counter = 0;
    var current = this.head;
    while (counter !== index) {
      current = current.next;
      counter++;
    }
    return current;
  }
  set(index, val) {
    let foundNode = this.get(index);
    if (foundNode) {
      foundNode.val = val;
    }
  }
}

var list = new SinglyLinkedList();

list.push('1')
list.push('2')
list.push('3')
list.set(0,'x')

Posted by youssefhoumazen 2020-11-14 05:40:10

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