Help with School Work

Hi I need help with a piece of JavaScript. I know this is Arduino but I dont know where else to ask for help. Sorry but i need to hand it in tomorrow. It is a calculator

var firstNum;
var secondNum;
alert('Welcome to the Coding Clubs first calculator!');
firstNum = prompt('Type in your first number please.');
SecondNum = prompt('Type in your second number please.');
var operator = prompt('Type in 1 to add, 2 to subtract, 3 to multiply, 4 to devide, and 5 to find modulo.');
switch (operator){
case '1':
var answer=firstNum+secondNum;
break;
case '2':
var answer= firstNum-secondNum;
break;
case '3':
var answer=firstNum*secondNum;
break;
case '4':
var answer=firstNum/secondNum;
break;
case '5':
var answer=firstNum%secondNum;
break;
default:
alert('Please retart. You messed up somewhere. Follow the instructions please');
break;
}
alert('The answer is ' + answer);
prompt('Type in 1 to add, 2 to subtract, 3 to multiply, 4 to devide,

"divide" is misspelled. Hope that helps!

Please retart. You messed up somewhere.

Heard of 'Google' its a very useful search engine ?

Try using it to search for 'Javascript Help Forums'

You will be amazed at the results ........

Stackoverflow is a good place to ask all kinds of programming questions http://stackoverflow.com/questions/tagged/javascript

But the OP probably needs to spell out why it doesn't work the way they expect.