Regular expression for not allowing spaces in the input field

Question

I have a username field in my form. I want to not allow spaces anywhere in the string. I have used this regex:

var regexp = /^\S/; 

This works for me if there are spaces between the characters. That is if username is ABC DEF. It doesn't work if a space is in the beginning, e.g. <space><space>ABC. What should the regex be?

Answer 1

While you have specified the start anchor and the first letter, you have not done anything for the rest of the string. You seem to want repetition of that character class until the end of the string:

var regexp = /^\S*$/; // a string consisting only of non-whitespaces 

Answer 2

Use + plus sign (Match one or more of the previous items),

var regexp = /^\S+$/