$(document).ready(function () {
  switch (this.operator) {
    case '+':
      this.ResultAns += this.first + this.second;
      break;
    case '-':
      this.ResultAns += this.first - this.second;
      break;
    case '*':
      this.ResultAns += this.first * this.second;
      break;
    case '/':
      this.ResultAns += this.first / this.second;
      break;
  }

first: string = "";
  second: string = "";
  operator: string = "";
  ResultAns: number;