title: JavaScript or jQuery equivalent of PHP's strstr() function
body: <p>Is there a function in jQuery or JavaScript that does the same as <code>strstr()</code> in PHP?</p>
  
  <p>I have an AJAX response that should be 1,2,3,12,13,23 or 123. I want to check if 1 exists, then if 2 exists then if 3 exists.</p>