title: Javascript function arguments with "-"
body: <p>I came across with strange issue. In my js file when i wrote a function with arguments and one of them was 'file-name'</p>
  
  <pre><code>function fileSize(id, file-name) {
    // some code
  }
  </code></pre>
  
  <p>This gave me an error, but when i changed argument name into "file_name", error was gone.</p>
  
  <pre><code>function fileSize(id, file_name) {
    // some code
  }
  </code></pre>
  
  <p>So why this happened??</p>