title: How to allow only a number (digits and decimal point) to be typed in an input?
body: <p>I am new to angularjs. I am wondering what is the way to allow only a valid number typed into a textbox.
  For example, user can type in "1.25", but cannot type in "1.a" or "1..".  When user try to type in the next character which will make it an invalid number, he cannot type it in.</p>
  
  <p>Thanks in advance.</p>