title: How to match with an exact string using regular expression
body: <p>I have small requirement.I want to search a string with exact match.
  Suppose i want to search for None_1, i am searching for 'None_1' using /None_1/, but it is matching even "xxxNone" but my requirement is it should match only None_[any digit].
  Here is my code  </p>
  
  <pre><code>/^None_+[0-9]{?}/
  </code></pre>
  
  <p>So it should match only None_1 , None_2</p>