Question

What is the regex to match a string with at least one period and no spaces?

Answer 1

You can use this :

/^\S*\.\S*$/

It works like this :

^    <-- Starts with
  \S   <-- Any character but white spaces (notice the upper case) (same as [^ \t\r\n])
  *    <-- Repeated but not mandatory
  \.   <--  A period
  \S   <-- Any character but white spaces
  *    <-- Repeated but not mandatory
$    <-- Ends here

You can replace \S by [^ ] to work strictly with spaces (not with tabs etc.)