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Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and a supportive community. Start your free trial today. # I prefer the alert to pop up as soon as a non-number is typed. Is there a more concise way than how I coded it?

The example given by Dave McFarland in the Practice If and Else exercise doesn't pop up an alert until after both values are entered, but I prefer the alert to pop up as soon as a non-number is typed (or if "cancel" is clicked). I came up with the code below to address that, but is there a shorter way to achieve the same result?

```// declare program variables
let num1;
let num2 = null;
let failMessage = 0;
let message;

// announce the program
alert("Let's do some math!");

// collect numeric input
num1 = prompt("Please type a number");
num1 = parseFloat(num1);

if (isNaN(num1)){
alert( "The value you typed is not a number. Reload and try again.");
failMessage = 1;
}

else if (num1 !== NaN) {

num2 = prompt("Please type another number");
num2 = parseFloat(num2);
}

if (num2 === 0){
alert("The second number is 0. You can't divide by zero. Reload and try again.");
failMessage = 1;
}

else if ( (isNaN(num2)) && (num1 !== NaN)){
alert( "The value you typed is not a number. Reload and try again.");
failMessage = 1;
}

// build an HTML message
message = `<h1>Math with the numbers \${num1} and \${num2}</h1>
\${num1} + \${num2} = \${num1 + num2}
<br>
\${num1} * \${num2} = \${num1 * num2}
<br>
\${num1} / \${num2} = \${num1 / num2}
<br>
\${num1} - \${num2} = \${num1 - num2}`;

// write message to web page
if (failMessage === 0){
document.write(message);
}
``` MOD

Try calling `parseFloat()` at the end of your prompt, so you don't have the pass the variables into it and call them so many times.

```   num1 = prompt("Please type a number").parseFloat();
``` This should avoid most cases of user input error:

```do {
var num1 = prompt("Please type a number");
if (isNaN(num1)) {
alert("The value you typed is not a number. Try again.");
}
} while (isNaN(num1));

do {
var num2 = prompt("Please type another number");
if (+num2 === 0) {
alert("The second number is 0. You can't divide by zero. Try again.");
} else if (isNaN(num2)) {
alert("The value you typed is not a number. Try again.");
} else {
result = true;
}
} while (+num2 === 0 || isNaN(num2));
```