From 81d7e1327709eff4b209e4a9088b4cfb43d23b18 Mon Sep 17 00:00:00 2001
From: Peter Mosses <18308236+pdmosses@users.noreply.github.com>
Date: Mon, 23 Jan 2023 19:25:40 +0100
Subject: [PATCH] Docs: add a migration guide (#1059)

The migration guide is intended to help those using Just the Docs (as a theme or a remote theme) switch from v0.3.3 to v0.4.0.

Co-authored-by: Matt Wang <matt@matthewwang.me>
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+---
+title: Migration and Upgrading
+layout: default
+---
+
+# Migrating and Upgrading
+
+Summary
+:   A site that uses `just-the-docs` (as a theme or as a remote them) automatically
+    switches to a new release, unless it is pinned to a previous version.
+
+    This migration guide draws attention to:
+
+    - changes that might break your site,
+    - features added in the latest release, and
+    - features that have become deprecated (and are likely to be removed in a future release).
+
+This document contains instructions on how to migrate and upgrade Just the Docs sites from every minor or major version bump, starting from `v0.3.3` to `v0.4.0`.
+
+<details open markdown="block">
+  <summary>
+    Table of contents
+  </summary>
+  {: .text-delta }
+- TOC
+{:toc}
+</details>
+
+{::options toc_levels="2..4" /}
+
+{: .warning }
+> If your configuration states `remote_theme: just-the-docs/just-the-docs`, your
+> website is built using the current `main` branch of the theme, which may include
+> changes made after the latest release; see the [CHANGELOG].
+>
+> If your configuration states `theme: just the docs` and your `Gemfile` specifies
+> `gem "just-the-docs"`, your website is always built using the latest release.
+
+{: .note }
+> If you have cloned/forked and customised the theme repo,
+> and pull the changes of a new release to your clone,
+> you may need to resolve merge conflicts.
+
+[CHANGELOG]: {{ site.baseurl }}{% link CHANGELOG.md %}
+
+## v0.3.3 … v0.4.x
+
+### REPOSITORY CHANGES
+
+#### Just the Docs
+
+The theme repo is now at <https://github.com/just-the-docs/just-the-docs>.
+The name of its default branch is now `main`.
+
+The theme docs website is now published at <https://just-the-docs.github.io/just-the-docs>.
+
+GitHub provides access to previous versions of the theme repo.
+You can browse [previous versions of the theme docs website] on the [Internet Archive].
+
+[previous versions of the theme docs website]: https://web.archive.org/web/20220000000000*/https://just-the-docs.github.io/just-the-docs
+[Internet Archive]: https://web.archive.org/
+
+The [README] page on the theme repo repeats much of the information from the [home page],
+formatted for browsing on GitHub.
+It also explains how to install the theme as a Ruby Gem, without creating a new site.
+
+[README]: https://github.com/just-the-docs/just-the-docs/blob/main/README.md
+[home page]: https://just-the-docs.github.io/just-the-docs
+
+#### Deploy previews
+
+When a PR builds successfully, Netlify provides a preview of how the theme docs website will look if the PR is merged.
+You can find links to the preview near the bottom of the Conversation tab of the PR.
+
+#### Just the Docs Template
+
+The template at <https://github.com/just-the-docs/just-the-docs-template>
+creates a repo with the minimal source files for a Just the Docs website.
+After configuring the relevant parameters, you can build and serve the website
+both locally and on GitHub Pages – using either Jekyll 3 or Jekyll 4!
+
+#### Just the Docs Tests
+
+The tests website at <https://just-the-docs.github.io/just-the-docs-tests>
+consists mainly of regression tests for bug fixes and new features.
+
+The test source files at <https://github.com/just-the-docs/just-the-docs-tests>
+illustrate the use of many Markdown and Jekyll features,
+including some that are not included in the theme docs.
+
+For example, see how to add support for rendering TeX/LaTeX [math formulas] with KaTeX and MathJax.
+
+[math formulas]: https://just-the-docs.github.io/just-the-docs-tests/components/math/index/
+
+### POTENTIALLY-BREAKING CHANGES in v0.4.0
+
+If switching to a new release of the theme breaks your website,
+check that you don't have any files in the `_includes`, `_layouts`, and `_sass`
+directories with the same names as files provided by the theme.
+
+If your repo has a customised copy of `_layouts/default.html` from a previous release,
+try removing it, or replace it by a fresh copy of the theme file.
+
+{: .warning }
+The following changes made in v0.4.0 *might* break or adversely affect your website
+when you next rebuild it, unless you have pinned it!
+
+#### New includes and SCSS
+
+Version 0.4.0 introduces many new `_includes` files. If you already have an existing include with the same name as a new addition, you will need to migrate or update that include. The new files are (relative to the `_includes` folder):
+
+- `mermaid_config.js`
+- `nav_footer_custom`
+- `search_placeholder_custom`
+- `toc_heading_custom`
+- the entire `components/` folder:
+  - `aux_nav`, `breadcrumbs`, `children_nav`, `footer`, `header`, `mermaid`, `search_footer`, `search_header`, `sidebar`
+- the entire `icons/` folder
+  - `code_copy`, `document`, `expand`, `external_link`, `icons`, `link`, `menu`, `search`
+- the entire `lunr/` folder
+  - `custom-data.json`, `custom-index.js`
+
+We have removed some code in `_sass/vendor` and added a new file at `_sass/custom/setup.scss`.
+
+#### favicons
+
+The file `_includes/favicon.html` is now ignored by the theme.
+If you're using it, your website's favicon is no longer displayed by browsers.
+
+To fix: Move the content of `_includes/favicon.html` to `_includes/head_custom.html`.
+
+#### Custom callout colors
+
+The file `_sass/custom/custom.scss` is now imported last: _after_ the configuration of callouts.
+If you've defined custom color variables for callouts in `_sass/custom/custom.scss`
+(and used them when configuring your callouts in `_config.yml`)
+you will not be able to rebuild your website.
+
+To fix: Move custom color variables for callouts in `_sass/custom/custom.scss` to `_sass/custom/variables.scss`.
+
+#### Pages and collections
+
+Links to ordinary pages now appear in the navigation on sites that use collections.
+You might want the navigation of your site to consist entirely of collections.
+
+To fix: Add the front matter `nav_exclude: true` to pages that the navigation should not display.
+
+#### Relative URLs
+
+All generated URLs are now relative.
+This is a bug fix, and unlikely to break any site.
+
+Relative links to pages within a website support deployment to different servers.
+
+#### Navigation order
+
+The order in which the navigation panel lists pages has been simplified.
+All pages with `nav_order` values now come before all pages that are ordered by `title`.
+
+If your website has a group of *sibling* pages where some siblings have `nav_order`
+string values, and others are ordered by numerical `title` values,
+the former now come before the latter.
+
+To fix: Add numerical `nav_order` values to the pages with numerical `title` values.
+
+### DEPRECATIONS
+
+{: .warning }
+The following features are deprecated, and to be removed in a future release.
+
+#### Jekyll 3
+
+You can still use Jekyll 3 (3.8.5 or later) to build websites using v0.4.0 of the theme.
+However, future releases of the theme may require the use of Jekyll 4.
+
+You can already use Jekyll 4 to build your website *locally*.
+It should look exactly the same as when built with Jekyll 3.[^Jekyll4]
+
+[^Jekyll4]:
+    Jekyll 4 depends on more recent versions of other gems than Jekyll 3,
+    and the differences between those versions may affect the files of your built site.
+
+To use Jekyll 4 when building your website *on GitHub Pages*, you need to run GitHub Actions.
+The simplest way of setting that up in a new repo is to create the repo using the Just the Docs template.
+To start running Jekyll 4 to build an existing repo on GitHub Pages,
+you can create a new repo with the template, then copy its `.github/workflows` directory,
+and update your repo settings to use Actions.
+
+#### Footer content configuration
+
+Currently, if your configuration sets `footer_content` to some text,
+the theme displays that text at the bottom of the main section of each page.
+
+The file `_includes/footer_custom.html` provides a more general way of customizing
+not only the text but also the markup for the page footer area.
+
+You can replicate the current display of `TEXT` in the footer using the following markup:
+
+```html
+<p class="text-small text-grey-dk-100 mb-0">TEXT</p>
+```
+
+### THEME WEBSITE CHANGES
+
+The website now uses *callouts*[^callouts] to draw attention to important information.
+
+[^callouts]:
+    The theme website configuration defines the callout titles and colors used there.
+    Websites that use the theme have to configure their own callout titles and colors.
+
+The theme uses [semantic versioning].
+A normal version number takes the form X.Y.Z,
+where X is the major version, Y is the minor version, and Z is the patch version.
+The theme uses version X.Y.Z.rcN for pre-release N of version X.Y.Z.
+When referring to version numbers on GitHub, we usually prefix them by 'v'.
+
+[semantic versioning]: https://semver.org
+
+Major version zero (0.Y.Z) is for initial development, where anything *may* change at any time.
+In practice, we increment the patch version Z for bug fixes and backwards compatible changes;
+we increment the minor version Y for changes that could break websites using the theme
+without pinning it to a specific version.
+
+The label `NEW` in the theme website indicates a feature that has been changed or added
+since the release of the previous *minor* version.
+For example, after the release of v0.4.Z, the theme website should label `NEW` all features that
+we have changed or added since v0.3.0 – not just since v0.3.3.
+When we release v0.5.0, we will remove all those labels, and add labels on features since v0.4.0.
+
+The theme docs website is not itself versioned.
+It changes incrementally, independently of theme releases.
+
+#### Home page
+
+The theme home page now focuses on the simplest ways of using the theme.
+It also notes the different behaviour of `theme` and `remote_theme` in connection
+with interim versions of the theme, such as pre-releases.
+
+#### CHANGELOG
+
+The CHANGELOG page lists the changes made in all previous releases and pre-releases of new versions of the theme gem.
+
+It also lists changes made to the `main` branch of the theme since the latest release or pre-release.
+
+For changes since v0.3.3, the log usually references the merged PR that made the change and its author.
+
+### NON-BREAKING CHANGES (OUTLINE ONLY)
+
+Brief descriptions of the following changes are to be added below.
+
+#### Accessibility
+
+- Skip to main content: the first keyboard-navigatable item is now a link to skip over the sidebar and header to the main content of the page. PR: [#949].
+- Aria-labels: improved `aria-label`s have been added to various site elements. PRs: [#950], ...
+- Other general improvements: gradual changes have improved tab focusability, contrast, and semantic elements. More work still to come. PRs: [#498], [#846]
+
+#### Configuration
+
+- Mermaid support: first-class support for [Mermaid](https://mermaid.js.org/) - a JavaScript-based diagram and charting tool supported by GitHub - has been added to the theme. **This feature is opt-in.** See the new doc subsections in [Configuration]({% link docs/configuration.md %}#mermaid-diagrams) and [Code]({% link docs/ui-components/code.md %}#mermaid-diagram-code-blocks) for more.
+- Multiple Google Analytics tags are now supported. PR: [#1029]
+
+#### Customization
+
+- all user-facing text is now customizable; previously, several elements (ex search placeholder) were hardwired into the theme. Now, users can blend custom includes and layouts to internationalize their sites.
+- we've clarified the role of `custom.scss` to be imported last; to allow users to define custom or override variables, we've added a new file `setup.scss`. PR: [#1135]
+
+#### Custom Includes
+
+We've added several custom `_includes` to provide users with more customization options for different site elements. We've also added a section to [Configuration]({% link docs/customization.md %}#override-includes) to outline these.
+
+All of these are opt-in by default; however, **these may be breaking if you have existing `_includes` with the same name**.
+
+Each item is listed with the relevant file and PR.
+
+- TOC heading: `toc_heading_custom.html`, PR: [#980]
+- Navigation panel footer: `nav_footer_custom.html`, PR: [#474]
+- Search placeholder: `search_placeholder_custom.html`, PR: [#613]
+- Modular site components: `components/` and `icons/`, PR: [#1058]
+- Custom search indices: `lunr/`, PR: [#1068]
+
+In a future (version 1) release, we may rename the custom include files.
+
+#### Modular Components
+
+We've broken up the default layout (`_layouts/default.html`) into multiple reusable components. This should have no impact on most users; however, it should make it easier to implement custom layouts.
+
+For more, see [Custom layouts and includes]({% link docs/customization.md %}#custom-layouts-and-includes). PR: [#1058].
+
+#### Navigation
+
+- Collections: nav panel shows links to ordinary pages before collections
+- Collection folding; part of "Combination". PR: [#578]
+- Scrolling to show link to selected page. PR: [#639]
+- External nav links are now supported. PR: [#876]
+- Child nav order: sort navigation pages with `child_nav_order`. PR: [#726]
+- Order when mixing different ways of specifying nav order
+
+#### Search
+
+In addition to customizing the search placeholder, we've also added the ability to provide custom content to the search index. for more, see [Custom content for search index]({% link docs/search.md %}#custom-content-for-search-index). PR: [#1068].
+
+#### Styling
+
+- Code copying: code blocks now allow users to easily copy their contents. PR: [#945]
+- Blockquote: shows vertical bar on left. PR: [#965]
+- Links wrap. PR: [#905]
+- Callouts: a new component similar to alerts or banners. See [UI Components - Callouts]({% link docs/ui-components/callouts.md %}). PR: [#466]
+
+----
+
+[#856]: https://github.com/just-the-docs/just-the-docs/pull/856
+[#806]: https://github.com/just-the-docs/just-the-docs/pull/806
+[#555]: https://github.com/just-the-docs/just-the-docs/pull/555
+[#814]: https://github.com/just-the-docs/just-the-docs/pull/814
+[#778]: https://github.com/just-the-docs/just-the-docs/pull/778
+[#221]: https://github.com/just-the-docs/just-the-docs/pull/221
+[#782]: https://github.com/just-the-docs/just-the-docs/pull/782
+[#549]: https://github.com/just-the-docs/just-the-docs/pull/549
+[#554]: https://github.com/just-the-docs/just-the-docs/pull/554
+[#499]: https://github.com/just-the-docs/just-the-docs/pull/499
+[#473]: https://github.com/just-the-docs/just-the-docs/pull/473
+[#835]: https://github.com/just-the-docs/just-the-docs/pull/835
+[#891]: https://github.com/just-the-docs/just-the-docs/pull/891
+[#906]: https://github.com/just-the-docs/just-the-docs/pull/906
+
+[#578]: https://github.com/just-the-docs/just-the-docs/pull/578
+[#463]: https://github.com/just-the-docs/just-the-docs/pull/463
+[#448]: https://github.com/just-the-docs/just-the-docs/pull/448
+[#466]: https://github.com/just-the-docs/just-the-docs/pull/466
+[#477]: https://github.com/just-the-docs/just-the-docs/pull/477
+[#495]: https://github.com/just-the-docs/just-the-docs/pull/495
+[#496]: https://github.com/just-the-docs/just-the-docs/pull/496
+[#498]: https://github.com/just-the-docs/just-the-docs/pull/498
+[#494]: https://github.com/just-the-docs/just-the-docs/pull/494
+[#639]: https://github.com/just-the-docs/just-the-docs/pull/639
+[#544]: https://github.com/just-the-docs/just-the-docs/pull/544
+[#364]: https://github.com/just-the-docs/just-the-docs/pull/364
+[#498]: https://github.com/just-the-docs/just-the-docs/pull/498
+[#613]: https://github.com/just-the-docs/just-the-docs/pull/613
+[#726]: https://github.com/just-the-docs/just-the-docs/pull/726
+[#474]: https://github.com/just-the-docs/just-the-docs/pull/474
+[#829]: https://github.com/just-the-docs/just-the-docs/pull/829
+[#857]: https://github.com/just-the-docs/just-the-docs/pull/857
+[#876]: https://github.com/just-the-docs/just-the-docs/pull/876
+[#909]: https://github.com/just-the-docs/just-the-docs/pull/909
+[#519]: https://github.com/just-the-docs/just-the-docs/pull/519
+[#855]: https://github.com/just-the-docs/just-the-docs/pull/855
+[#686]: https://github.com/just-the-docs/just-the-docs/pull/686
+[#495]: https://github.com/just-the-docs/just-the-docs/pull/495
+[#846]: https://github.com/just-the-docs/just-the-docs/pull/846
+[#727]: https://github.com/just-the-docs/just-the-docs/pull/727
+[#889]: https://github.com/just-the-docs/just-the-docs/pull/889
+[#893]: https://github.com/just-the-docs/just-the-docs/pull/893
+[#905]: https://github.com/just-the-docs/just-the-docs/pull/905
+[#898]: https://github.com/just-the-docs/just-the-docs/pull/898
+
+[#950]: https://github.com/just-the-docs/just-the-docs/pull/950
+[#944]: https://github.com/just-the-docs/just-the-docs/pull/944
+[#939]: https://github.com/just-the-docs/just-the-docs/pull/939
+[#949]: https://github.com/just-the-docs/just-the-docs/pull/949
+[#941]: https://github.com/just-the-docs/just-the-docs/pull/941
+[#956]: https://github.com/just-the-docs/just-the-docs/pull/956
+[#935]: https://github.com/just-the-docs/just-the-docs/pull/935
+[#940]: https://github.com/just-the-docs/just-the-docs/pull/940
+[#951]: https://github.com/just-the-docs/just-the-docs/pull/951
+[#955]: https://github.com/just-the-docs/just-the-docs/pull/955
+[#937]: https://github.com/just-the-docs/just-the-docs/pull/937
+
+[#965]: https://github.com/just-the-docs/just-the-docs/pull/965
+[#960]: https://github.com/just-the-docs/just-the-docs/pull/960
+[#962]: https://github.com/just-the-docs/just-the-docs/pull/962
+[#964]: https://github.com/just-the-docs/just-the-docs/pull/964
+[#967]: https://github.com/just-the-docs/just-the-docs/pull/967
+[#974]: https://github.com/just-the-docs/just-the-docs/pull/974
+[#980]: https://github.com/just-the-docs/just-the-docs/pull/980
+[#985]: https://github.com/just-the-docs/just-the-docs/pull/985
+[#986]: https://github.com/just-the-docs/just-the-docs/pull/986
+[#992]: https://github.com/just-the-docs/just-the-docs/pull/992
+
+[#945]: https://github.com/just-the-docs/just-the-docs/pull/945
+[#999]: https://github.com/just-the-docs/just-the-docs/pull/999
+[#1000]: https://github.com/just-the-docs/just-the-docs/pull/1000
+[#1001]: https://github.com/just-the-docs/just-the-docs/pull/1001
+[#1010]: https://github.com/just-the-docs/just-the-docs/pull/1010
+[#1015]: https://github.com/just-the-docs/just-the-docs/pull/1015
+[#1018]: https://github.com/just-the-docs/just-the-docs/pull/1018
+[#1019]: https://github.com/just-the-docs/just-the-docs/pull/1019
+[#1021]: https://github.com/just-the-docs/just-the-docs/pull/1021
+[#1027]: https://github.com/just-the-docs/just-the-docs/pull/1027
+[#1029]: https://github.com/just-the-docs/just-the-docs/pull/1029
+[#1040]: https://github.com/just-the-docs/just-the-docs/pull/1040
+[#1061]: https://github.com/just-the-docs/just-the-docs/pull/1061
+[#1065]: https://github.com/just-the-docs/just-the-docs/pull/1065
+[#1071]: https://github.com/just-the-docs/just-the-docs/pull/1071
+[#1074]: https://github.com/just-the-docs/just-the-docs/pull/1074
+[#1076]: https://github.com/just-the-docs/just-the-docs/pull/1076
+[#1077]: https://github.com/just-the-docs/just-the-docs/pull/1077
+[#1090]: https://github.com/just-the-docs/just-the-docs/pull/1090
+[#1091]: https://github.com/just-the-docs/just-the-docs/pull/1091
+[#1092]: https://github.com/just-the-docs/just-the-docs/pull/1092
+[#1095]: https://github.com/just-the-docs/just-the-docs/pull/1095
+
+[#1068]: https://github.com/just-the-docs/just-the-docs/pull/1068
+[#1135]: https://github.com/just-the-docs/just-the-docs/pull/1135
-- 
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