//Global variables

var prevCalc = 0;

var calc = "";

//The following function displays a number in the textfield when a number is clicked.

//Note that it keeps concatenating numbers which are clicked.

function showNum(value) {

document.frmCalc.txtNumber.value += value;

}

//The following function decreases the value of displayed number by 1.

//isNaN method checks whether the value passed to the method is a number or not.

function decrement() {

var num = parseFloat(document.frmCalc.txtNumber.value);

if (!(isNaN(num))) {

num--;

document.frmCalc.txtnumber.value = num;

}

}

//The following function is called when "Add" button is clicked.

//Note that it also changes the values of the global variables.

function add() {

var num = parseFloat(document.frmCalc.txtNumber.value);

if (!(isNaN(num))) {

prevCalc = num;

document.frmCalc.txtNumber.value = "";

calc = "Add";

}

}

//The following function is called when "Calculate" button is clicked.

//Note that this function is dependent on the value of global variable.

function calculate() {

var num = parseFloat(document.frmCalc.txtNumber.value);

if (!(isNaN(num))) {

if (calc == "Add"){

var total = previousCalc + num;

document.frmCalc.txtNumber.value = total;

}

}

function clear() {

document.frmCalc.txtNumber.value = "";

prevCalc = 0;

calc = "";

}

}

This is code that I was given. I am supposed to fix the synax errors which I have done. However, the add function does not seem to work when I implement this calculator. Can someone take a look at the add function and see why it is not adding two numbers together. In javascript. Thanks so much!