Disraptor: Limitations for documents and resources

Disraptor can only operate reliably while imposing restrictions on its documents and resources.

List of restrictions

URL paths must not be file-relative

URL paths in scripts and stylesheets must not be file-relative. Disraptor is not able to resolve the following reference reliably:

body {
  background-image: url("tiled-background.jpg");

Instead, use root-relative URL paths (or absolute URLs).

body {
  background-image: url("/img/tiled-background.jpg");


URL references in Disraptor documents and resources must either be absolute or root-relative. The correct context of file-relative URLs cannot be recovered; hence, they must be avoided.

In the following example, two routes are specified. One for a document (/example → http://localhost:8080/); one for stylesheets (/css/* → http://localhost:8080/css/*). In the example document, there is a reference to the stylesheet /css/styles.css:


<link rel="stylesheet" href="/css/styles.css">

The stylesheet contains the following styles of URL references: absolute, root-relative and file-relative.


@import "http://localhost:8080/css/base.css";
@import "/css/colors.css";
@import "typography.css";

The first two styles (absolute and root-relative URLs) can always be resolved correctly. The root-relative URL will recover its context via its route and resolve to http://localhost:8080/css/colors.css.

The third style (a file-relative URL) causes an issue. This will not match any Disraptor route because a Disraptor route has to begin with a slash: It’s always root-relative to the Discourse instance. Therefore, the last reference will resolve to typography.css (note the missing http://localhost:8080/), potentially pointing to a resource on the Discourse instance or to a non-existing object. It’s not possible for Disraptor to recover the original context of this reference without looking at the content of each document or resource at the language level.

For this reason, file-relative URLs must not be used in Disraptor applications. Every URL reference in your stylesheets and scripts has to be absolute or root-relative.

HTML IDs, class names and custom attributes should be prefixed

Note: This limitation only applies to stylesheets when using the legacy rendering mode. The shadow DOM rendering mode achieves style isolation and avoids these conflicts.

HTML IDs, classes and custom attributes should be prefixed to avoid conflicts with Discourse. Following this limitation avoids styles from leaking out of the Disraptor document into the surrounding Discourse document. It also avoids Discourse accidentally selecting or querying DOM nodes by ID, class name or custom attribute that are part of the Disraptor document.

The following CSS will conflict with Discourse’s button styles and affect not only the Disraptor document but also the surrounding Discourse document.

.btn {
  outline: 2px solid red;

[data-attr] {
 /* … */

Instead, prefix IDs, class names, and custom attributes.

.app-btn {
  outline: 2px solid red;

[data-app-attr] {
 /* … */

Stylesheets and scripts must not select or query DOM nodes outside of a Disraptor document

Stylesheets and scripts must not select or query DOM nodes outside of a Disraptor document. Following this limitation avoids styles from leaking from the Discourse document into the containing Disraptor document. It also avoids Disraptor accidentally selecting or querying DOM nodes by ID, class name or custom attribute that are part of the Discourse document.

This limitation may be intentionally ignored if one wants to make use of Discourse functionality or styles (e.g. styling buttons the same way Discourse does).

Inline scripts must not be depending on external scripts

Since Ember only injects Disraptors content into the Discourse context there is no real rendering of the embedded DOM-part. Because of that scripts inside the embedded website would not be executed. Disraptor solves this issue by extracting all of the scripts into the Discourse context where they get rendered later.

This comes with the limitation, that the scripts are executed in the order they are ready to and cannot be deferred. Since inline scripts do not have to be downloaded before being executed they will (almost always) be executed before external scripts are. If, on the other hand, these inline scripts need functions which are defined in the external scripts, they will just throw an error instead of doing what they are supposed to.

Therefore Disraptor cannot guarantee for correctly rendering a website having these dependencies. A workaround is moving the part of an internal script, which contains the references to external scripts, into a external script itself and sourcing it after the initial external script. External scripts which are injected into a DOM will be executed in order of appearance, so this will resolve the issues but results in slightly longer website loading times.

Don’t load jQuery twice

Rather an information than a restriction: if you use jQuery for your web-application Disraptor won’t load the jquery.js script. This is because Discourse already uses jQuery and we would therefore load it twice. If we would do that there could be version differences causes broken functionality in Discourse. Same applies of course if you use jquery.slim.js.

Fontawesome icons

You can use fontawesome icons without any problems with Disraptor. But they don’t quite work out of the box. There is one tiny thing you have to do to make them work. When you have your Discourse set up and running go to the Settings and search for svg icon subset. Enter all the icons your application uses there. Discourse will load these for you and Disraptor embeds them into the website.