Hooks

Hooks is a method of augmenting or altering the behavior of the process, with custom callbacks.

List of hooks

Relative to the global pipeline

Name	Description	Arguments
`init`	Called after parsing the book, before generating output and pages.	None
`finish:before`	Called after generating the pages, before copying assets, cover, ...	None
`finish`	Called after everything else.	None

Relative to the page pipeline

It is recommended using templating to extend page parsing.

Name	Description	Arguments
`page:before`	Called before running the templating engine on the page	Page Object
`page`	Called before outputting and indexing the page.	Page Object

:memo: HonKit may skip these pages hooks on non-changed page when incremental mode(honkit serve)

Page Object

{
    // Parser named
    "type": "markdown",

    // File Path relative to book root
    "path": "page.md",

    // Absolute file path
    "rawpath": "/usr/...",

    // Title of the page in the SUMMARY
    "title": "",

    // Content of the page
    // Markdown/Asciidoc in "page:before"
    // HTML in "page"
    "content": "<h1>Hello</h1>"

    // Level of the page
    "level": "1.5.3.1"

    // Depth of the page
    "depth": "3"

    // Other attributes appear in the .md between two '---' at the beginning of the content
    // For example in the front of the markdown:
    // ---
    // description: This is a description
    // ---
    "description": "This is a description"

    // Previous article
    "previous": Article Object

    // Next article
    "next": Article Object
}

Example to add a title

In the page:before hook, page.content is the markdown/asciidoc content.

{
    "page:before": function(page) {
        page.content = "# Title\n" +page.content;
        return page;
    }
}

Example to replace some html

In the page hook, page.content is the HTML generated from the markdown/asciidoc conversion.

{
    "page": function(page) {
        page.content = page.content.replace("<b>", "<strong>")
            .replace("</b>", "</strong>");
        return page;
    }
}

Asynchronous Operations

Hooks callbacks can be asynchronous and return promises.

Example:

{
    "init": function() {
        return writeSomeFile()
        .then(function() {
            return writeAnotherFile();
        });
    }
}