calculator method

calculator.js

rnc.calculator = function () {
  rnc.Display.init($("#displayPanel")[0]);

  $(".key").on('touchstart', function (event) {
    var key = $(this).attr("data-rnc-tag"),
      id = this.id;

    // this is a performance boost
    event.preventDefault();
    event.stopPropagation();
    switch (id) {
      case "key0":
      case "key1":
      case "key2":
      case "key3":
      case "key4":
      case "key5":
      case "key6":
      case "key7":
      case "key8":
      case "key9":
      case "keyDecimalPoint":
        rnc.Display.enterDigit(key);
        break;
      case "keyC":
        rnc.Display.clearDisplay();
        break;
      case "keyCe":
        rnc.Display.clearError();
        break;
      case "keyAdd":
        rnc.Display.setOperator("+");
        break;
      case "keySubtract":
        rnc.Display.setOperator("-");
        break;
      case "keyMultiply":
        rnc.Display.setOperator("*");
        break;
      case "keyDivide":
        rnc.Display.setOperator("/");
        break;
      case "keyEquals":
        rnc.Display.setOperator("=");
        break;
      case "keyPercent":
        rnc.Display.setPercent();
        break;
      case "keyPlusMinus":
        rnc.Display.reverseSign();
        break;
    }
    return false;
  });
}