Using the PluginAPI in Site Customizations

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Using the client side Plugin API is the safest way to build Discourse Javascript plugins and themes while respecting backwards compatibility.

However, some people have made simple customizations using the Admin > Customization > CSS/HTML and dropping some Javascript into a <script> tag. Previously, it was very difficult to use the withPluginApi to access objects using the Discourse container.

In the latest tests-passed build of Discourse I’ve added the ability to use the pluginAPI via a site customation.

To use it, you just need to add some attributes to a script tag in your </HEAD> customization:

<script type="text/discourse-plugin" version="0.1">
  // you can use the `api` object here!
  api.decorateCooked($elem => $elem.css({ backgroundColor: 'yellow' }));
</script>

When you save the customization, Discourse will transpile the ES2015 code within the tag so you can use the latest Javascript features. Additionally, it wraps the code in an initializer and runs it through withPluginApi so you don’t have to bother with that. Just specify the version of the api object you want and Discourse will give it to you, providing safe backwards compatibility.

If the compilation of the ES2015 fails for some reason, when you view source on your page you’ll see the error in a <script type='text/discourse-js-error'> block. Fix what it says and re-save your customization and you’ll be good to go.

This document is version controlled - suggest changes on github.

Last edited by @JammyDodger 2024-05-26T08:40:50Z

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2

What’s the best way to “import” as a Site Customisation? - is it just to use require?

Whilst this works:

<script type="text/discourse-plugin" version="0.1">
var HamburgerMenuComponent = require('discourse/components/hamburger-menu').default;
</script>

This does not:

<script type="text/discourse-plugin" version="0.1">
import {default as HamburgerMenuComponent2 } from 'discourse/components/hamburger-menu';

</script>

Where I get this error:

<script type="text/discourse-js-error">unknown: 'import' and 'export' may only appear at the top level (3:0)
  1 | Discourse._registerPluginCode('0.1', api => {
  2 |   
> 3 | import {default as HamburgerMenuComponent2 } from 'discourse/components/hamburger-menu';
    | ^
  4 | 
  5 | 
  6 | }); at <eval>:8695:14</script>
2 Likes
3

Instead of importing it, you can look it up with

api.container.lookupFactory('component:hamburger-menu')
5 Likes
4

Is there a way to get access to the h helper from virtual-dom in a site customization? I’m trying to add a simple dropdown widget to use in our header, and I can’t get that darned h, even though I can get createWidget

5

Does:

h = require('virtual-dom').h;

not work?

2 Likes
6

Yes it does! Works perfectly, thanks a ton!

7

I wouldn’t recommend doing it that way as it would likely break future compatibility. You can use this for now but I’ll try to introduce a workaround shortly that will be safer long term.

5 Likes
8

Makes sense, it’s kinda circumventing the whole Plugin API thing and relying on implementation details of the ES6 compilation output, both things that are Dangerous™

Anyways, I’ll definitely keep an eye out for a better solution

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I’ll try to get to it soon and I’ll reply in this topic, so watch it and you’ll see :slight_smile:

4 Likes
10

Actually thinking about it, the decorateWidget helper gets called with an object that has the h method. How are you inserting your widget if not via a decorator?

If you could post code that would be helpful.

11

{{mount-widget}} in a template for a plugin outlet.

1 Like
12

Ah that’s clever – I didn’t think people would try that. Okay, let me try something out.

13

Okay, I’ve added h to the pluginApi object as long as you request plugin api v0.3:

<script type="text/discourse-plugin" version="0.3">
  console.log(api.h('b', ['hello', 'world']));
</script>

That should work for you!

https://github.com/discourse/discourse/commit/b10b6c673d5f4936d0ee107e16531df106fae75e

9 Likes