title: JavaScript error invalid quantifier
body: <p>This javascript code: </p>
  
  <pre><code>var regex = /(?&lt;=&lt;img src=").*?(?=")/gm;
  var src = regex.match(str); 
  </code></pre>
  
  <p>Gives me this error: </p>
  
  <pre><code>SyntaxError: invalid quantifier ?&lt;=&lt;img src=").*?(?=")
      in eval() line 0
  </code></pre>
  
  <p>What is the problem?</p>