---
id: 64007367d54d2a7efbf44fcf
title: Step 12
challengeType: 0
dashedName: step-12
---
# --description--
Next, you need to check if the value returned by the `parseInt()` function is a number or not.
To do that, you can use the `isNaN()` function. This function takes in a string or number as an argument, and returns `true` if it evaluates to `NaN`. For example:
```js
isNaN("test"); // true
isNaN(2); // false
isNaN("3.5"); // false
```
Update the second condition in your `if` statement to use the `isNaN()` function to check if the value returned by `parseInt()` is `NaN`.
Also,as we mentioned in step 1 that we are considering only positive numbers, we should add a third condition in `if` statement to check whether the number is less than 0 (i.e negative numbers)
```js
6 < 0; // false
-1 < 0; // true
-8 < 0; // true
0 < 0; //false
```
# --hints--
You should wrap the value returned by `parseInt()` in the `isNaN()` function. And add a third condition which checks the value returned by `parseInt()` to be less than 0.
```js
assert.match(String(checkUserInput), /if\s*\(\s*!\s*numberInput\s*\.\s*value\s*\|\|\s*isNaN\(\s*parseInt\(\s*numberInput\s*\.\s*value\s*\)\s*\)\s*\|\|\s*parseInt\(\s*numberInput\s*\.\s*value\s*\)\s*\<\s*0\s*\)\s*\{/);
```
The body of your `if` statement within `checkUserInput` should be empty.
```js
assert.match(String(checkUserInput), /if\s*\(\s*.+\s*\)\s*\{\s*\}/);
```
# --seed--
## --seed-contents--
```html
Decimal to Binary Converter