A minimal example of a Watson Dialog XML script with an inline Javascript function.

ibm-watson-dialog-with-inline-javascript-function.xml

<?xml version="1.0" encoding="UTF-8" ?>
<dialog xsi:noNamespaceSchemaLocation="WatsonDialogDocument_1.0.xsd"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<flow>
<folder label="Main">

  <output id="start">
    <prompt>
      <item>Write stuff and I’ll SHOUT it back to you.</item>
    </prompt>
  </output>

  <getUserInput>
    <input>
      <grammar>
        <item>(ANYTHING)={anything}</item>
      </grammar>

      <function>
        <script>
          Name=Calculate
          Line="{anything.source}!!!".toUpperCase()
        </script>
        <action varName="anything" operator="SET_TO">{MCT:CUSTOM:Calculate:value}</action>
        <output>
          <prompt>
            <item>{anything}</item>
          </prompt>
        </output>
      </function>
    </input>
  </getUserInput>

</folder>
</flow>

<entities>
  <entity name="ANYTHING">
    <value>
      <grammar>
        <item>!.*</item>
      </grammar>
    </value>
  </entity>
</entities>

<variables>
  <var_folder name="Home">
    <var name="anything" type="TEXT" />
  </var_folder>
</variables>

</dialog>