Scripts

Trilium supports creating "code" notes, i.e. notes which contain some sort of formal code - be it programming language (C++, JavaScript), structured data (JSON, XML) or other types of codes (CSS etc.).

This can be useful for few things:

• computer programmers can store code snippets as notes
• JavaScript code notes can be executed inside Trilium for some extra functionality
  • we call such JavaScript code notes "scripts"
• JSON, XML etc. can be used as storage for structured data (typically used in conjunction with scripting)

Scripting

To go further I must explain basic architecture of Trilium - in its essence it is a classic web application - it has these two main components:

• frontend running in the browser (using HTML, CSS, JavaScript) - this is mainly used to interact with the user, display notes etc.
• backend running JavaScript code in node.js runtime - this is responsible for e.g. storing notes, encrypting them etc.

So we have frontend and backend, each with their own set of responsibilities, but their common feature is that they both run JavaScript code. Add to this the fact, that we're able to create JavaScript code notes and we're onto something.

Button use case

Let's take a look at our demo script (shipped with default Trilium document) - Task manager. One of the things this script does is adding a button to the Trilium interface which will allow user to easily add new Task (TODO item).

First take a look at the red circle all the way on the top - this what we want to achieve - new button in UI which will create new note representing a task/todo item.

Red point below the first one marks the note type we have create for this script - it's "JavaScript frontend". It's frontend because adding button to UI is clearly frontend responsibility.

In the note content you can see the code which calls one of the API methods, this one is specifically meant to add new buttons. Code needs to set few button properties:

• button title
• icon which should appear on the button
• optional shortcut under which you can trigger the button
• most importantly "action" - what must happen when button is clicked

Action handler

Saving the note to the database is backend's responsibility so we immediately pass control to the backend and ask it to create a note. Once this is done, we show the newly created note so that the user can set the task title and maybe some attributes.

Script execution

So we have a script which will add the button to the toolbar. But how can we execute it? One possibility is to click on "play" icon (marked by red circle). The problem with this is that this UI change is time bound by Trilium runtime so when we restart Trilium, button won't be there.

We need to execute it every time Trilium starts up, but we probably don't want to have to manually click on play button on every start up.

The solution is marked by red circle at the bottom - this note has label @run=frontendStartup - this is one of the "system" labels which Trilium understands. As you might guess, this will cause all such labeled script notes to be executed once Trilium frontend starts up.

Events

In general we may say that script notes are triggered by events. "run" represents global events:

• run
  • frontendStartup - executes on frontend upon startup
  • backendStartup - executes on backend upon startup
  • hourly - executes once an hour on backend
  • daily - executes once a day on backend

Other events are bound to some entity, these are defined as relations - meaning that script is triggered only if note has this script attached to it through relations (or it can inherit it).

• runOnNoteView - executes when note is displayed on frontend
• runOnNoteCreation - executes when note is created on backend
• runOnNoteTitleChange - executes when note title is changed (includes note creation as well)
• runOnNoteChange - executes when note is changed (includes note creation as well)
• runOnChildNoteCreation - executes when new note is created under this note
• runOnAttributeCreation - executes when new attribute is created under this note
• runOnAttributeChange - executes when attribute is changed under this note

Script API

To do anything useful, Trilium publishes "Script API". Actually there are two such APIs:

• Frontend API
• Backend API