How to allow only character and spaces to be filled in input field

How to allow only character and spaces to be filled in input field

  
i have a user registration form ,which contains input field which corressponds to  First name 


I want to allow only character and spaces to be filled in that input field .

can any 1 tell me how to achieve it
You'll need to use a mask input component. There are some in the forge, but I suggest to you try Custom Masks.