How to validate a letter and whitespace only input via JavaScript regular expression

Question

I have an input type=\"text\" for names in my HTML code. I need to make sure that it is a string with letters from \'a\' to \'z\' and \'A\' to \'Z\' only, along

Answer 1

If you are building something for modern browsers, there is something very pleasurable in HTML5:

Reference: HTML5 forms input types

Update 2017/01/17:

Old browsers are quite weak on the market shares nowadays. This is a good practice to use HTML5 features instead of compatibility scripts.