title: parse error using esprima for file while optimizing js files with r.js
body: <p>I am optimizing several js files into one using <code>r.js</code>. It works fine before. Recently,I modified some js code, add the code as:</p>
  
  <pre><code>var x = 08;
  </code></pre>
  
  <p>then it shows </p>
  
  <blockquote>
    <p>ERROR:parse error using esprima for file D://webroot/js/a.js</p>
    
    <p>ERROR:line 45: Unexpected token ILLEGAL.</p>
  </blockquote>
  
  <p>Line 45 is where I add <code>var x = 08</code>, and <code>09</code> will show error too. It seemed that numbers begining with 0 meanwhile containing <code>8</code> or <code>9</code> is illegal. Maybe they were treated as bese 8 number .. ?</p>
  
  <p>How can I let <code>r.js</code> ignore this point and still optimizie js files? </p>