what to if I want to check whether input was a number or not by javascript only.

Question

I tried to write a code for it please mention the error.
https://code.sololearn.com/WvXXEoU924jw/?ref=app

Answer 1

You can use
if (isNaN(x.value))

But for number only input, you should set your input as number
use
<input type="number" >

Answer 2

Thanks @Calvin

Answer 3

Always check commands on Mozilla document
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/isNaN

Answer 4

But I want in which part of javascript we learn about NaN type things?