title: Javascript Regex - get variable from sentence
body: <p>I want create simple AI for youtube in javascript. I want to write into input string like "Find Pranks on youtube". And that word "Prank" is variable... Everyone can write whatever thay want,but it must be sentence "Find 'something' on youtube". I tried to create regex, but it's to hard for me. Is it posible to do this like that?</p>
  
  <p>The regex I tried is:  <code>\\Find\s\[abc]\s\\on\\youtube/i;</code></p>
  
  <p>HTML Code:</p>
  
  <pre><code>&lt;input type="text" id="uq" class="input auto-size"/&gt;
  &lt;button id="button" onclick="question();" class="button" href="javascript:;"&gt;Ask&lt;/button&gt;
  </code></pre>
  
  <p>Javascript Code:</p>
  
  <pre><code>function question()
      const findonyoutube = /(?&lt;=find)(.*)(?=on youtube)/gm;
      var str = document.getElementById('uq').value;
      if(findonyoutube.test(str))
      {
      alert(findonyoutube.exec(str)[0]);
      }
  }
  </code></pre>
  
  <p>Not working, it return <code>Uncaught TypeError: Cannot read property '0' of null</code></p>