MissingThisQualifier.qhelp

<!DOCTYPE qhelp PUBLIC
  "-//Semmle//qhelp//EN"
  "qhelp.dtd">
<qhelp>
<overview>
<p>
JavaScript methods can call other methods of the same class instance through the use of the <code>this</code> keyword.
In other object-oriented languages such as Java, the use of the <code>this</code> keyword for such method calls is optional. It is however <em>not</em> optional in JavaScript.
If the <code>this</code> keyword is left out, the call is a regular function call. 
</p>

</overview>
<recommendation>

<p>
Add the <code>this</code> keyword as the receiver of the call.
</p>

</recommendation>
<example>

<p>
In the following example, the call to <code>setAudioProperties</code> will call an undeclared global function, and <em>not</em> the method defined later in the class.
</p>

<sample src="examples/MissingThisQualifier1.js" />

<p>
The problem can be fixed by adding the <code>this</code> keyword to the call: <code>this.setAudioProperties()</code>.
</p>

</example>
<references>
<li>MDN: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes">Classes</a></li>
</references>
</qhelp>