Polymer 1.0: Do <script> tags go inside or outside the <dom-module>?

Question

Question

Which method of placing the <script> tags is "best-practice?"

• Inside the <dom-module>?

or

• Outside the <dom-module>?

Also, please answer:

1. Why?
2. What is the source of your answer?
3. What downside risks are there by doing it the "wrong" way?

---

Polymer Starter Kit: OUTSIDE

In the Polymer Starter Kit, the my-list.html and my-greeting.html files place the <script> tag outside the <dom-module>.

Like this:

<dom-module>
  <style>...</style>
  <template>...</template>
<dom-module>
<script>...</script>

---

Other Experts: INSIDE

However, I have heard and seen several examples from Google employees and Google developers that suggest the <script> tags should go inside the <dom-module>.

Like this:

<dom-module>
  <style>...</style>
  <template>...</template>
  <script>...</script>
<dom-module>

Peltz

Answer 1

The correct answer is - it shouldn't matter. While the documentation is indeed as @Mowzer noted, this is just an example rather than a definition. At least some actual Polymer elements like e. g. iron-image have it outside dom-module.

The relationship between the dom-module and the object Polymer constructor defines is established through the 'is' property of the object passed to the Polymer constructor and the id attribute of the dom-module.

From Local DOM guide:

Give the <dom-module> an id attribute that matches its element’s is property and put a inside the <dom-module>. Polymer will automatically clone this template’s contents into the element’s local DOM.

As a side note, you can also successfully use <script src="external.js"></script> to separate the html from the JS - I'm just guessing this is one possible reason for this question. The only drawback to this (AFAIK) is that in this case a vulcanized version of your element will show incorrect (offset) code line numbers for JS errors.

Labourer

And some Polymer elements have no <dom-module> at all, e.g. <iron-selector> and <iron-ajax>. They only have a <script> element. The <dom-module> is necessary to define styles and <template>. If your element requires neither then a <script> element containing the Polymer({ ... }) call will suffice. – Lilybel

Answer 2

Looks like <script> tags should go inside the <dom-module>.

Per this definition in the developer guide.

Element definition

<dom-module id="element-name">

  <template>
    <style>
      /* CSS rules for your element */
    </style>

    <!-- local DOM for your element -->

    <div>{{greeting}}</div> <!-- data bindings in local DOM -->
  </template>

  <script>
    // element registration
    Polymer({
      is: "element-name",

      // add properties and methods on the element's prototype

      properties: {
        // declare properties for the element's public API
        greeting: {
          type: String,
          value: "Hello!"
        }
      }
    });
  </script>

</dom-module>

Peltz