a href='https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/String'>String</a></span></td><td><span> file creation mode</span></td></tr><tr><td><span class="method-depth0"></span><code>callback</code><span class="pull-right label label-optional">optional</span></td><td><span><a href='https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Function'>Function</a>(error, fd)</span></td><td><span> the callback function</span></td></tr><tr><td><span class="method-depth1"></span><cod