calculator.js Example File

 Function.prototype.bind = function() {
     var func = this;
     var thisObject = arguments[0];
     var args = Array.prototype.slice.call(arguments, 1);
     return function() {
         return func.apply(thisObject, args);
     }
 }

 function Calculator(ui)
 {
     this.ui = ui;

     this.pendingAdditiveOperator = Calculator.NO_OPERATOR;
     this.pendingMultiplicativeOperator = Calculator.NO_OPERATOR;
     this.sumInMemory = 0;
     this.sumSoFar = 0;
     this.factorSoFar = 0;
     this.waitingForOperand = true;

     with (ui) {
         display.text = "0";

         zeroButton.clicked.connect(this.digitClicked.bind(this, 0));
         oneButton.clicked.connect(this.digitClicked.bind(this, 1));
         twoButton.clicked.connect(this.digitClicked.bind(this, 2));
         threeButton.clicked.connect(this.digitClicked.bind(this, 3));
         fourButton.clicked.connect(this.digitClicked.bind(this, 4));
         fiveButton.clicked.connect(this.digitClicked.bind(this, 5));
         sixButton.clicked.connect(this.digitClicked.bind(this, 6));
         sevenButton.clicked.connect(this.digitClicked.bind(this, 7));
         eightButton.clicked.connect(this.digitClicked.bind(this, 8));
         nineButton.clicked.connect(this.digitClicked.bind(this, 9));

         pointButton.clicked.connect(this, "pointClicked");
         changeSignButton.clicked.connect(this, "changeSignClicked");

         backspaceButton.clicked.connect(this, "backspaceClicked");
         clearButton.clicked.connect(this, "clear");
         clearAllButton.clicked.connect(this, "clearAll");

         clearMemoryButton.clicked.connect(this, "clearMemory");
         readMemoryButton.clicked.connect(this, "readMemory");
         setMemoryButton.clicked.connect(this, "setMemory");
         addToMemoryButton.clicked.connect(this, "addToMemory");

         divisionButton.clicked.connect(this.multiplicativeOperatorClicked.bind(this, Calculator.DIVISION_OPERATOR));
         timesButton.clicked.connect(this.multiplicativeOperatorClicked.bind(this, Calculator.TIMES_OPERATOR));
         minusButton.clicked.connect(this.additiveOperatorClicked.bind(this, Calculator.MINUS_OPERATOR));
         plusButton.clicked.connect(this.additiveOperatorClicked.bind(this, Calculator.PLUS_OPERATOR));

         squareRootButton.clicked.connect(this.unaryOperatorClicked.bind(this, Calculator.SQUARE_OPERATOR));
         powerButton.clicked.connect(this.unaryOperatorClicked.bind(this, Calculator.POWER_OPERATOR));
         reciprocalButton.clicked.connect(this.unaryOperatorClicked.bind(this, Calculator.RECIPROCAL_OPERATOR));
         equalButton.clicked.connect(this, "equalClicked");
     }
 }

 Calculator.NO_OPERATOR = 0;
 Calculator.SQUARE_OPERATOR = 1;
 Calculator.POWER_OPERATOR = 2;
 Calculator.RECIPROCAL_OPERATOR = 3;
 Calculator.DIVISION_OPERATOR = 4;
 Calculator.TIMES_OPERATOR = 5;
 Calculator.MINUS_OPERATOR = 6;
 Calculator.PLUS_OPERATOR = 7;

 Calculator.prototype.abortOperation = function()
 {
     this.clearAll();
     this.ui.display.text = "####";
 }

 Calculator.prototype.calculate = function(rightOperand, pendingOperator)
 {
     if (pendingOperator == Calculator.PLUS_OPERATOR) {
         this.sumSoFar += rightOperand;
     } else if (pendingOperator == Calculator.MINUS_OPERATOR) {
         this.sumSoFar -= rightOperand;
     } else if (pendingOperator == Calculator.TIMES_OPERATOR) {
         this.factorSoFar *= rightOperand;
     } else if (pendingOperator == Calculator.DIVISION_OPERATOR) {
         if (rightOperand == 0)
             return false;
         this.factorSoFar /= rightOperand;
     }
     return true;
 }

 Calculator.prototype.digitClicked = function(digitValue)
 {
     if ((digitValue == 0) && (this.ui.display.text == "0"))
         return;
     if (this.waitingForOperand) {
         this.ui.display.clear();
         this.waitingForOperand = false;
     }
     this.ui.display.text += digitValue;
 }

 Calculator.prototype.unaryOperatorClicked = function(op)
 {
     var operand = this.ui.display.text - 0;
     var result = 0;
     if (op == Calculator.SQUARE_OPERATOR) {
         if (operand < 0) {
             this.abortOperation();
             return;
         }
         result = Math.sqrt(operand);
     } else if (op == Calculator.POWER_OPERATOR) {
         result = Math.pow(operand, 2);
     } else if (op == Calculator.RECIPROCAL_OPERATOR) {
         if (operand == 0.0) {
             this.abortOperation();
             return;
         }
         result = 1 / operand;
     }
     this.ui.display.text = result + "";
     this.waitingForOperand = true;
 }

 Calculator.prototype.additiveOperatorClicked = function(op)
 {
     var operand = this.ui.display.text - 0;

     if (this.pendingMultiplicativeOperator != Calculator.NO_OPERATOR) {
         if (!this.calculate(operand, this.pendingMultiplicativeOperator)) {
             this.abortOperation();
             return;
         }
         this.ui.display.text = this.factorSoFar + "";
         operand = this.factorSoFar;
         this.factorSoFar = 0;
         this.pendingMultiplicativeOperator = Calculator.NO_OPERATOR;
     }

     if (this.pendingAdditiveOperator != Calculator.NO_OPERATOR) {
         if (!this.calculate(operand, this.pendingAdditiveOperator)) {
             this.abortOperation();
             return;
         }
         this.ui.display.text = this.sumSoFar + "";
     } else {
         this.sumSoFar = operand;
     }

     this.pendingAdditiveOperator = op;
     this.waitingForOperand = true;
 }

 Calculator.prototype.multiplicativeOperatorClicked = function(op)
 {
     var operand = this.ui.display.text - 0;

     if (this.pendingMultiplicativeOperator != Calculator.NO_OPERATOR) {
         if (!this.calculate(operand, this.pendingMultiplicativeOperator)) {
             this.abortOperation();
             return;
         }
         this.ui.display.text = this.factorSoFar + "";
     } else {
         this.factorSoFar = operand;
     }

     this.pendingMultiplicativeOperator = op;
     this.waitingForOperand = true;
 }

 Calculator.prototype.equalClicked = function()
 {
     var operand = this.ui.display.text - 0;

     if (this.pendingMultiplicativeOperator != Calculator.NO_OPERATOR) {
         if (!this.calculate(operand, this.pendingMultiplicativeOperator)) {
             this.abortOperation();
             return;
         }
         operand = this.factorSoFar;
         this.factorSoFar = 0.0;
         this.pendingMultiplicativeOperator = Calculator.NO_OPERATOR;
     }
     if (this.pendingAdditiveOperator != Calculator.NO_OPERATOR) {
         if (!this.calculate(operand, this.pendingAdditiveOperator)) {
             this.abortOperation();
             return;
         }
         this.pendingAdditiveOperator = Calculator.NO_OPERATOR;
     } else {
         this.sumSoFar = operand;
     }

     this.ui.display.text = this.sumSoFar + "";
     this.sumSoFar = 0.0;
     this.waitingForOperand = true;
 }

 Calculator.prototype.pointClicked = function()
 {
     if (this.waitingForOperand)
         this.ui.display.text = "0";
     if (this.ui.display.text.indexOf(".") == -1)
         this.ui.display.text += ".";
     this.waitingForOperand = false;
 }

 Calculator.prototype.changeSignClicked = function()
 {
     var text = this.ui.display.text;
     var value = text - 0;

     if (value > 0) {
         text = "-" + text;
     } else if (value < 0) {
         text = text.slice(1);
     }
     this.ui.display.text = text;
 }

 Calculator.prototype.backspaceClicked = function()
 {
     if (this.waitingForOperand)
         return;

     var text = this.ui.display.text;
     text = text.slice(0, -1);
     if (text.length == 0) {
         text = "0";
         this.waitingForOperand = true;
     }
     this.ui.display.text = text;
 }

 Calculator.prototype.clear = function()
 {
     if (this.waitingForOperand)
         return;

     this.ui.display.text = "0";
     this.waitingForOperand = true;
 }

 Calculator.prototype.clearAll = function()
 {
     this.sumSoFar = 0.0;
     this.factorSoFar = 0.0;
     this.pendingAdditiveOperator = Calculator.NO_OPERATOR;
     this.pendingMultiplicativeOperator = Calculator.NO_OPERATOR;
     this.ui.display.text = "0";
     this.waitingForOperand = true;
 }

 Calculator.prototype.clearMemory = function()
 {
     this.sumInMemory = 0.0;
 }

 Calculator.prototype.readMemory = function()
 {
     this.ui.display.text = this.sumInMemory + "";
     this.waitingForOperand = true;
 }

 Calculator.prototype.setMemory = function()
 {
     this.equalClicked();
     this.sumInMemory = this.ui.display.text - 0;
 }

 Calculator.prototype.addToMemory = function()
 {
     this.equalClicked();
     this.sumInMemory += this.ui.display.text - 0;
 }