How do I restrict a single line text field to 15 characters only?

[hemanth16]

Hi,

I need to restrict the first name and last name fields more than 15 letters 

Can you help me on script?

Thanks in Advance!!

[Yousaf · Accepted solution]

Can you please try 
g_form.addErrorMessage Instead of showErrorBox.

[Yousaf]

or use 

g_form.showFieldMsg('');

[hemanth16]

Hi Yousaf,

Can you help me on the script ?

first name + last name should not be greater than 15

Thanks in Advance!!