# Client-side hooks

Most of these hooks are called during or in order to set up the formatting
process.

## documentReady
Called from: `src/templates/pad.html`

Things in context:

nothing

This hook proxies the functionality of jQuery's `$(document).ready` event.

## aceDomLinePreProcessLineAttributes

Called from: `src/static/js/domline.js`

Things in context:

1. domline - The current DOM line being processed
2. cls - The class of the current block element (useful for styling)

This hook is called for elements in the DOM that have the "lineMarkerAttribute"
set. You can add elements into this category with the aceRegisterBlockElements
hook above. This hook is run BEFORE the numbered and ordered lists logic is
applied.

The return value of this hook should have the following structure:

`{ preHtml: String, postHtml: String, processedMarker: Boolean }`

The preHtml and postHtml values will be added to the HTML display of the
element, and if processedMarker is true, the engine won't try to process it any
more.

## aceDomLineProcessLineAttributes

Called from: `src/static/js/domline.js`

Things in context:

1. domline - The current DOM line being processed
2. cls - The class of the current block element (useful for styling)

This hook is called for elements in the DOM that have the "lineMarkerAttribute"
set. You can add elements into this category with the aceRegisterBlockElements
hook above. This hook is run AFTER the ordered and numbered lists logic is
applied.

The return value of this hook should have the following structure:

`{ preHtml: String, postHtml: String, processedMarker: Boolean }`

The preHtml and postHtml values will be added to the HTML display of the
element, and if processedMarker is true, the engine won't try to process it any
more.

## aceCreateDomLine

Called from: `src/static/js/domline.js`

Things in context:

1. domline - the current DOM line being processed
2. cls - The class of the current element (useful for styling)

This hook is called for any line being processed by the formatting engine,
unless the aceDomLineProcessLineAttributes hook from above returned true, in
which case this hook is skipped.

The return value of this hook should have the following structure:

`{ extraOpenTags: String, extraCloseTags: String, cls: String }`

extraOpenTags and extraCloseTags will be added before and after the element in
question, and cls will be the new class of the element going forward.

## acePostWriteDomLineHTML

Called from: `src/static/js/domline.js`

Things in context:

1. node - the DOM node that just got written to the page

This hook is for right after a node has been fully formatted and written to the
page.

## aceAttribsToClasses

Called from: `src/static/js/linestylefilter.js`

Things in context:

1. linestylefilter - the JavaScript object that's currently processing the ace
   attributes
2. key - the current attribute being processed
3. value - the value of the attribute being processed

This hook is called during the attribute processing procedure, and should be
used to translate key, value pairs into valid HTML classes that can be inserted
into the DOM.

The return value for this function should be a list of classes, which will then
be parsed into a valid class string.

## aceAttribClasses

Called from: `src/static/js/linestylefilter.js`

Things in context:
1. Attributes - Object of Attributes

This hook is called when attributes are investigated on a line. It is useful if
you want to add another attribute type or property type to a pad.

Example:
```
exports.aceAttribClasses = function(hook_name, attr, cb){
  attr.sub = 'tag:sub';
  cb(attr);
}
```

## aceGetFilterStack

Called from: `src/static/js/linestylefilter.js`

Things in context:

1. linestylefilter - the JavaScript object that's currently processing the ace
   attributes
2. browser - an object indicating which browser is accessing the page

This hook is called to apply custom regular expression filters to a set of
styles. The one example available is the ep_linkify plugin, which adds internal
links. They use it to find the telltale `[[ ]]` syntax that signifies internal
links, and finding that syntax, they add in the internalHref attribute to be
later used by the aceCreateDomLine hook (documented above).

## aceEditorCSS

Called from: `src/static/js/ace.js`

Things in context: None

This hook is provided to allow custom CSS files to be loaded. The return value
should be an array of resource urls or paths relative to the plugins directory.

## aceInitInnerdocbodyHead

Called from: `src/static/js/ace.js`

Things in context:

1. iframeHTML - the HTML of the editor iframe up to this point, in array format

This hook is called during the creation of the editor HTML. The array should
have lines of HTML added to it, giving the plugin author a chance to add in
meta, script, link, and other tags that go into the `<head>` element of the
editor HTML document.

## aceEditEvent

Called from: `src/static/js/ace2_inner.js`

Things in context:

1. callstack - a bunch of information about the current action
2. editorInfo - information about the user who is making the change
3. rep - information about where the change is being made
4. documentAttributeManager - information about attributes in the document (this
   is a mystery to me)

This hook is made available to edit the edit events that might occur when
changes are made. Currently you can change the editor information, some of the
meanings of the edit, and so on. You can also make internal changes (internal to
your plugin) that use the information provided by the edit event.

## aceRegisterNonScrollableEditEvents

Called from: `src/static/js/ace2_inner.js`

Things in context: None

When aceEditEvent (documented above) finishes processing the event, it scrolls
the viewport to make caret visible to the user, but if you don't want that
behavior to happen you can use this hook to register which edit events should
not scroll viewport. The return value of this hook should be a list of event
names.

Example:
```
exports.aceRegisterNonScrollableEditEvents = function(){
  return [ 'repaginate', 'updatePageCount' ];
}
```

## aceRegisterBlockElements

Called from: `src/static/js/ace2_inner.js`

Things in context: None

The return value of this hook will add elements into the "lineMarkerAttribute"
category, making the aceDomLineProcessLineAttributes hook (documented below)
call for those elements.

## aceRegisterLineAttributes

Called from: `src/static/js/ace2_inner.ts`

Things in context: None

Tells Etherpad which line attributes should be preserved when a user presses
Enter to split a line. Without this hook, custom line attributes (such as
headings or alignment) are lost when a line is split.

The return value should be an array of attribute names:

```
exports.aceRegisterLineAttributes = function(){
  return [ 'heading' ];
}
```

When Enter is pressed on a line that has a registered attribute:

* **Middle or end of line:** the attribute is copied to the new line below.
* **Start of line (column 0):** the attribute moves down with the text content,
  and the now-empty line above is cleared.

This is backwards compatible — on Etherpad versions that do not have this hook,
the registration is silently ignored.

## aceInitialized

Called from: `src/static/js/ace2_inner.js`

Things in context:

1. editorInfo - information about the user who will be making changes through
   the interface, and a way to insert functions into the main ace object (see
   ep_headings)
2. rep - information about where the user's cursor is
3. documentAttributeManager - some kind of magic

This hook is for inserting further information into the ace engine, for later
use in formatting hooks.

## postAceInit

Called from: `src/static/js/pad.js`

Things in context:

1. ace - the ace object that is applied to this editor.
2. clientVars - Object containing client-side configuration such as author ID
   and plugin settings. Your plugin can manipulate this object via the
   `clientVars` server-side hook.
3. pad - the pad object of the current pad.

## postToolbarInit

Called from: `src/static/js/pad_editbar.js`

Things in context:

1. ace - the ace object that is applied to this editor.
2. toolbar - Editbar instance. See below for the Editbar documentation.

Can be used to register custom actions to the toolbar.

Usage examples:

* [https://github.com/tiblu/ep_authorship_toggle]()

## postTimesliderInit

Called from: `src/static/js/timeslider.js`

There doesn't appear to be any example available of this particular hook being
used, but it gets fired after the timeslider is all set up.

## goToRevisionEvent

Called from: `src/static/js/broadcast.js`

Things in context:

1. rev - The newRevision

This hook gets fired both on timeslider load (as timeslider shows a new
revision) and when the new revision is showed to a user. There doesn't appear to
be any example available of this particular hook being used.

## userJoinOrUpdate

Called from: `src/static/js/pad_userlist.js`

Things in context:

1. info - the user information

This hook is called on the client side whenever a user joins or changes. This
can be used to create notifications or an alternate user list.

## `chatNewMessage`

Called from: `src/static/js/chat.js`

This hook runs on the client side whenever a chat message is received from the
server. It can be used to create different notifications for chat messages. Hook
functions can modify the `author`, `authorName`, `duration`, `rendered`,
`sticky`, `text`, and `timeStr` context properties to change how the message is
processed. The `text` and `timeStr` properties may contain HTML and come
pre-sanitized; plugins should be careful to sanitize any added user input to
avoid introducing an XSS vulnerability.

Context properties:

* `authorName`: The display name of the user that wrote the message.
* `author`: The author ID of the user that wrote the message.
* `text`: Sanitized message HTML, with URLs wrapped like `<a
  href="url">url</a>`. (Note that `message.text` is not sanitized or processed
  in any way.)
* `message`: The raw message object as received from the server, except with
  time correction and a default `authorId` property if missing. Plugins must not
  modify this object. Warning: Unlike `text`, `message.text` is not
  pre-sanitized or processed in any way.
* `rendered` - Used to override the default message rendering. Initially set to
  `null`. If the hook function sets this to a DOM element object or a jQuery
  object, then that object will be used as the rendered message UI. Otherwise,
  if this is set to `null`, then Etherpad will render a default UI for the
  message using the other context properties.
* `sticky` (boolean): Whether the gritter notification should fade out on its
  own or just sit there until manually closed.
* `timestamp`: When the chat message was sent (milliseconds since epoch),
  corrected using the difference between the local clock and the server's clock.
* `timeStr`: The message timestamp as a formatted string.
* `duration`: How long (in milliseconds) to display the gritter notification (0
  to disable).

## `chatSendMessage`

Called from: `src/static/js/chat.js`

This hook runs on the client side whenever the user sends a new chat message.
Plugins can mutate the message object to change the message text or add metadata
to control how the message will be rendered by the `chatNewMessage` hook.

Context properties:

* `message`: The message object that will be sent to the Etherpad server.

## `chatPrefillFromUser`

Called from: `src/static/js/pad_userlist.ts`

Called when the user clicks an entry in the user list. The default behavior is to
open the chat panel and prefill the input with `@<name> `, where `<name>` is that
user's display name (with whitespace replaced by underscores). Plugins can return
a different prefill string from their callback — the first non-empty string
returned wins.

Typical use is by AI/bot plugins whose author display name (e.g. "AI Assistant")
isn't a useful @-mention; the plugin can substitute its trigger string instead.

Context properties:

* `authorId`: The clicked user's author id.
* `name`: The clicked user's display name.
* `prefill`: The default prefill string Etherpad would otherwise use.

Example:

```javascript
exports.chatPrefillFromUser = (hookName, {authorId, name}, cb) => {
  if (authorId === window.clientVars.ep_my_bot.authorId) return cb('@bot ');
  return cb();
};
```

## collectContentPre

Called from: `src/static/js/contentcollector.js`

Things in context:

1. cc - the contentcollector object
2. state - the current state of the change being made
3. tname - the tag name of this node currently being processed
4. styl - the style applied to the node (probably CSS) -- Note the typo
5. cls - the HTML class string of the node

This hook is called before the content of a node is collected by the usual
methods. The cc object can be used to do a bunch of things that modify the
content of the pad. See, for example, the heading1 plugin for etherpad original.

E.g. if you need to apply an attribute to newly inserted characters, call
cc.doAttrib(state, "attributeName") which results in an attribute
attributeName=true.

If you want to specify also a value, call cc.doAttrib(state,
"attributeName::value") which results in an attribute attributeName=value.


## collectContentImage

Called from: `src/static/js/contentcollector.js`

Things in context:

1. cc - the contentcollector object
2. state - the current state of the change being made
3. tname - the tag name of this node currently being processed
4. style - the style applied to the node (probably CSS)
5. cls - the HTML class string of the node
6. node - the node being modified

This hook is called before the content of an image node is collected by the
usual methods. The cc object can be used to do a bunch of things that modify the
content of the pad.

Example:

```
exports.collectContentImage = function(name, context){
  context.state.lineAttributes.img = context.node.outerHTML;
}

```

## collectContentPost

Called from: `src/static/js/contentcollector.js`

Things in context:

1. cc - the contentcollector object
2. state - the current state of the change being made
3. tname - the tag name of this node currently being processed
4. style - the style applied to the node (probably CSS)
5. cls - the HTML class string of the node

This hook is called after the content of a node is collected by the usual
methods. The cc object can be used to do a bunch of things that modify the
content of the pad. See, for example, the heading1 plugin for etherpad original.

## handleClientMessage_`name`

Called from: `src/static/js/collab_client.js`

Things in context:

1. payload - the data that got sent with the message (use it for custom message
   content)

This hook gets called every time the client receives a message of type `name`.
This can most notably be used with the new HTTP API call, "sendClientsMessage",
which sends a custom message type to all clients connected to a pad. You can
also use this to handle existing types.

`collab_client.js` has a pretty extensive list of message types, if you want to
take a look.

## aceStartLineAndCharForPoint-aceEndLineAndCharForPoint

Called from: src/static/js/ace2_inner.js

Things in context:

1. callstack - a bunch of information about the current action
2. editorInfo - information about the user who is making the change
3. rep - information about where the change is being made
4. root - the span element of the current line
5. point - the starting/ending element where the cursor highlights
6. documentAttributeManager - information about attributes in the document

This hook is provided to allow a plugin to turn DOM node selection into
[line,char] selection. The return value should be an array of [line,char]

## aceKeyEvent

Called from: `src/static/js/ace2_inner.js`

Things in context:

1. callstack - a bunch of information about the current action
2. editorInfo - information about the user who is making the change
3. rep - information about where the change is being made
4. documentAttributeManager - information about attributes in the document
5. evt - the fired event

This hook is provided to allow a plugin to handle key events.
The return value should be true if you have handled the event.

## collectContentLineText

Called from: `src/static/js/contentcollector.js`

Things in context:

1. cc - the contentcollector object
2. state - the current state of the change being made
3. tname - the tag name of this node currently being processed
4. text - the text for that line

This hook allows you to validate/manipulate the text before it's sent to the
server side. To change the text, either:

* Set the `text` context property to the desired value and return `undefined`.
* (Deprecated) Return a string. If a hook function changes the `text` context
  property, the return value is ignored. If no hook function changes `text` but
  multiple hook functions return a string, the first one wins.

Example:

```
exports.collectContentLineText = (hookName, context) => {
  context.text = tweakText(context.text);
};
```

## collectContentLineBreak

Called from: `src/static/js/contentcollector.js`

Things in context:

1. cc - the contentcollector object
2. state - the current state of the change being made
3. tname - the tag name of this node currently being processed

This hook is provided to allow whether the br tag should induce a new magic
domline or not. The return value should be either true(break the line) or false.

## disableAuthorColorsForThisLine

Called from: `src/static/js/linestylefilter.js`

Things in context:

1. linestylefilter - the JavaScript object that's currently processing the ace
   attributes
2. text - the line text
3. class - line class

This hook is provided to allow whether a given line should be deliniated with
multiple authors. Multiple authors in one line cause the creation of magic span
lines. This might not suit you and now you can disable it and handle your own
deliniation. The return value should be either true(disable) or false.

## aceSetAuthorStyle

Called from: `src/static/js/ace2_inner.js`

Things in context:

1. dynamicCSS - css manager for inner ace
2. outerDynamicCSS - css manager for outer ace
3. parentDynamicCSS - css manager for parent document
4. info - author style info
5. author - author info
6. authorSelector - css selector for author span in inner ace

This hook is provided to allow author highlight style to be modified. Registered
hooks should return 1 if the plugin handles highlighting. If no plugin returns
1, the core will use the default background-based highlighting.

## aceSelectionChanged

Called from: `src/static/js/ace2_inner.js`

Things in context:

1. rep - information about where the user's cursor is
2. documentAttributeManager - information about attributes in the document

This hook allows a plugin to react to a cursor or selection change,
perhaps to update a UI element based on the style at the cursor location.