WebIDL thing is not defined

Defining WebIDL things

You probably landed here because you got a warning like:

• attribute thing not defined in SomeInterface.

This is trying to tell you that you forgot to define this part of the interface. Or that you forgot to explicitly define the interface itself!

Tl;dr:

• Add data-dfn-for="SomeInterface" data-dfn-for="SomeInterface" to container <section>.
• Change SomeInterface to the name of the Interface, Dictionary, or Enum you are defining.
• Now use <dfn> to define the methods, attributes, or enum values.

Full example below...

What you need to do

Given:

<section>
<pre class="idl">
interface SomeInterface {
  readonly attribute DOMString thing;
}
</pre>
</section>

You want to add the following:

<!-- 
  1. add data-dfn-for, and data-link-for to section,
     with the name of the interface, dictionary, or enum 
     you are defining. 
--> 
<section data-dfn-for="SomeInterface" data-dfn-for="SomeInterface">

  <!-- 2. explicitly define the interface: in the heading works best! -->
  <h2><dfn>SomeInterface</dfn> interface</h2>

  <pre class="idl">
  interface SomeInterface {
    readonly attribute DOMString thing;
    OtherInterface someMethod();
  }
  </pre>
   
  <!-- 3. Actually write something meaningful about the interface -->
  <p>The <a>SomeInterface</a> let's you do really neat things!</p>

  <!-- 4. define the `thing` attribute -->
  <section>
    <h3><dfn>thing</dfn> attribute</h3>
    <p>The <a>thing</a> attribute, when getting, gives you the thing.</p> 
  </section>

  <!-- 5. define the `someMethod()` attribute -->
  <section>
    <h3><dfn>someMethod()</dfn> attribute</h3>
    <p>The <a>thing</a> attribute, when getting, gives you the thing.</p> 
  </section>
</section>

The above structure will give result in a nice structure for users. The ToC and links will all work as expected.

Defined in a different spec?

If the OtherInterface interface is defined in a different spec, then all you need to do is link to it like this:

<p>
  The <code><dfn data-cite="SOME-SPEC#dom-SomeThing"> OtherInterface</dfn></code>
  interface is defined by [[!SOME-SPEC]].
</p>