how to validate textbox input using javascript?

Question

I am accepting an input in the textbox i want to check following conditions:
1)alert if textbox is left blank
2)check if textbox is given spaces in it
3)numbers cannot be entered
4)after giving an alert after proper message the focus(cursor)should be in that textbox

Answer 1

Answer 2

Yuor textbox:


Javascript:

Answer 3

you won't be able to regulate a field cost utilizing an onclick tag. the most elementary way I see you are able to doing that is installation a Hypertext Preprocessor document that you'll link to, and which connects the database and modifies the field. any opposite direction you are able to attempt that is to verify an HTML form and put up the recommendations both to a distinct Hypertext Preprocessor document or an identical document (only in a placed up technique). you ought to maintain any vulnerabilities, obviously, in both of those strategies.