RegEx for Empty textbox but also check for spaces and tabs

Hello,

I need the help of the experts on this forum.

I would like to come up with a RegEx (javascript) to validate a textbox which has any blank spaces in it, any blank tabs in it, and also check for an empty textbox?

ie.
alert("Accepted")
------------------------------
Jameswithsometext
Billy Jean

alert("Not accepted")
------------------------------
- inadvertenly typed blank spaces
- inadvertenly typed tabs
- blank textbox

Easiest would be to find a non-whitespace character and negate the check, like

Or there's the more literal "contains only whitespace if anything at all",

Thanks so much. Worked like a charm