How to detect a white space inside a Textbox? and run a function if detected

How would you go about it to check that a white space have been entered inside a Textbox would you use string.find or string.gmatch or something Completely different? I want this to run a function every time a white space is entered

I know there is alternative ways like detect that the player is focused and if space button is pressed but that's not the way I won't to go about it