class Stack{ constructor(){ this.data=[]; } push(val){ this.data.push(val); return this; } peek(){ return this.data[this.data.length--]; } pop(){ this.data.pop(); return this; } } const myStack = new Stack(); console.log(myStack.push('google')); console.log(myStack.push('udemy')); console.log(myStack.push('linkedin')); console.log(myStack.pop());