Getting a integer value from a textbox, how to check if it's NaN or null etc?

Question

I am pulling a value via JavaScript from a textbox. If the textbox is empty, it returns NaN. I want to return an empty string if it\'s null, empty, etc.

Answer 1

You can also do it this way:

var number = +input.value;
if (input.value === "" || number != number)
{
    // not a number
}

NaN is equal to nothing, not even itself.

if you don't like to use + to convert from String to Number, use the normal parseInt, but remember to always give a base

var number = parseInt(input.value, 10)

otherwise "08" becomes 0 because Javascript thinks it's an octal number.