Checking if input is empty?

Question

How can I check if the input is empty for this code? I usually do something like this:

if(number == "") {
//Code to execute
}

But that doesn't seem to work if a space or multiple spaces is present. For example, add that to the code, then input a space and press the button. It returns "is divisible by 2." I'd have to individually add each number of spaces. Is there a way around this?

https://code.sololearn.com/W71keXUbAKcL/#html

Answer 1

if(number.trim() === "") {
//Code to execute
}

Answer 2

Use
number.trim()

Answer 3

Can I have an example? I have no idea where to put that xD

amnotsmart