## CHANGES IN bookdown VERSION 0.30

• Support specific markdown content like list or code chunk inside Theorem and Proof special environments (#1371).

• Fix regression about special usage of bookdown project not using index.Rmd as main file. It is recommended to use index.Rmd in all projects, but workflow has been improved for other cases (thanks, @otoomet, #1349).

## CHANGES IN bookdown VERSION 0.29

CRAN release: 2022-09-12

• The argument code_folding works for the gitbook() output format now (thanks, @atusy, #1368).

• Setting toc_depth or toc_float in bs4_book() will now throw an error like toc to make it clear that TOC is not an opt-out choice and can’t be customize (thanks, @karlmay88, #1377).

## CHANGES IN bookdown VERSION 0.28

CRAN release: 2022-08-09

• Fix fontawesome 4.7 CSS that is included with gitbook() format styling. Now new icons (like fa-usb) are correctly available as expected (thanks, @snipfoo, #1353).

• Fix an issue with clipboard button in gitbook() (thanks, @chadyuu, #1358).

## CHANGES IN bookdown VERSION 0.27

CRAN release: 2022-06-14

• Fix fence_theorems() so that output is not ignored anymore. With previous version, when output was different than NULL, the result was written to input, ignoring output value. From now on, set input and output to the same file if you want to overwrite (thanks, @Scinawa, #1342).

• Tweak bs4_book() default CSS for better support of python chunk highlighting (thanks, @briandk, #1333).

• Fix an issue with guessing output format when no output_format is provided in render_book() for files in a rmd_subdir folder (thanks, @shivam7898, #1331).

• Fix the issue of the invisible gitbook toolbar on iPad (thanks, @mpereira-dev, #60).

## CHANGES IN bookdown VERSION 0.26

CRAN release: 2022-04-15

• Fix issues with TOC in gitbook() and Pandoc 2.18 (thanks, @avraam-inside, #1326, #1329).

• Fix an issue with per-format rmd_files config when no output_format was provided in render_book() (thanks, @ellessenne, #1323).

• Added support for theorem/proof environments back for Word/EPUB/ODT output (thanks, @N0rbert, #1313).

• kindlegen() is defunct now.

## CHANGES IN bookdown VERSION 0.25

CRAN release: 2022-03-16

### NEW FEATURES

• Set option bookdown.theorem.enabled = FALSE to opt-out bookdown special Theorem and Proof environment syntax. options(bookdown.theorem.enabled = FALSE) must be called before the function to render the book, e.g in a project’s .Rprofile. This can be useful for advanced users who only want PDF output and needs to handle themselves the environment using LaTeX directly, or Custom Blocks syntax without bookdown interfering (thanks, @finkelshtein, #1285).

• bs4_book() gains a footnotes_inline argument. Set to FALSE to opt-out the default behavior of moving footnotes inline to show on hover (thanks, @Pindar777, #1253).

### BUG FIXES

• Fix styling of bibliography for bs4_book() (thanks, @Selbosh, #1277).

• Fix an issue with Pandoc 2.17 and internationalization of Proof-like environment (#1302).

• Fix an issue with Pandoc 2.17 and cross referencing sections in non HTML format (thanks, @N0rbert, #1301).

• Fix an issue with Pandoc 2.15 and footnote relocation in each chapter (#1275).

• Fix an issue with html_book() and toc.css not working correctly with recent pandoc (thanks, @florisvdh, #1268).

• Fix an issue with unneeded header-attr.js inserted by rmarkdown while bookdown already cleans attributes (thanks, @salim-b, #865).

### MAJOR CHANGES

• The theorem and proof knitr engines no longer use the block2 knitr engine to create theorem/proof environments, but write out fenced Divs instead, which is the new syntax for these environments. Note that this means these environments are no longer supported in EPUB output (they work only in HTML and PDF), but hopefully the support will be back in the future (thanks, @deleeuw, #1178).

• The tag <meta property="og:url"> has been removed from the default HTML template and the gitbook template (thanks, @jtbayly, #970).

## CHANGES IN bookdown VERSION 0.24

CRAN release: 2021-09-02

### MAJOR CHANGES

• The default search engine for gitbook has been changed from lunr to fuse. If you want to switch back to lunr, you may set:

output:
bookdown::gitbook:
config:
search:
engine: lunr

### MINOR CHANGES

• Reverted the fix for #1223 since it only affects a specific version of Pandoc (2.14.1). If this issue affects you, please see #1223 for workarounds.

• bs4_book() now has the template argument like gitbook() (thanks, @shinneuro, #1247).

### BUG FIXES

• extra_dependencies in gitbook() will now be appended after Gitbook’s dependencies so that it does not get overridden (thanks, @ThierryO, @linogaliana, #1101, #1248).

• Fix an issue with Fenced Divs for Theorem & Proof environments in the Lua filter (thanks, @tchevri, #1233).

• gitbook(self_contained = TRUE) was slow when the output contains base64-encoded images (thanks, @king2bob, #1236).

• The search config search: true or search: false for gitbook throws a misleading error (thanks, @GegznaV, #1238).

## CHANGES IN bookdown VERSION 0.23

CRAN release: 2021-08-13

### NEW FEATURES

• This version has included a new RStudio template project to start an HTML book in bookdown::gitbook or bookdown::bs4_book. Template projects can be created using the RStudio IDE menu “New Project”, or using one of the two new functions, create_gitbook() or create_bs4_book(), to easily create the template that you want to start with from within the R console (#225, #1123, #1201).

• Added an argument global_numbering to most output format functions in this package to control the figure/table numbering scheme (thanks, @elfunesto #948, @Kodiologist #1057). If TRUE, number figures and tables globally throughout a document (e.g., Figure 1, Figure 2, …). If FALSE, number them sequentially within sections (e.g., Figure 1.1, Figure 1.2, …, Figure 5.1, Figure 5.2, …). Previously, this numbering scheme was hard-coded internally according to the number_sections argument (global_numbering = !number_sections). Now the two arguments have become independent, e.g., you can use global_numbering = TRUE with number_sections = TRUE.

• For HTML book formats, a default 404.html page will now be created if none exists already. This page can be customized by adding a _404.md or _404.Rmd file which will be rendered to HTML and inserted in the book. Most web serving platforms (e.g. Netlify, GH Pages, etc.) will use this file named 404.html in the root as a custom error page. Otherwise, like browsers do, a default 404 page is shown. For context, a 404 error indicates that the file can’t be found, and it happens when a browser can’t find a requested web page. This could happen with your online book if you shared a link to a section but change the name of this section leading to a change in url (#1035).

• The bookdown::gitbook output format now supports an alternative search engine, namely fuse.js, which has several advantages over lunr.js, the previous search engine for gitbook. Using fuse.js will fix a number of long-standing issues such as #734, #735, and #792. To enable fuse.js, set the search engine to be fuse in gitbook’s config in YAML, e.g.,

output:
bookdown::gitbook:
config:
search:
engine: fuse

Depending on user feedback, we may set fuse to be the default search engine in a future version of bookdown. We will appreciate your testing and feedback!

• bs4_book(splib_bib = TRUE) can now be specified to have the same effect as in gitbook(). References will be shown at the end of each chapter and not only at the end of the book. This is useful with bs4_book() when a citation style not supporting footnotes is used because in that case, references are not shown inline in popups (thanks, @shirdekel, #1185).

• In bs4_book(), improvement regarding copy button:

• It has now a light icon instead of a text with white background (#1192).
• It will no more show on output block code when knitr’s option is collapse = FALSE (#1197).
• It will now be placed correctly on the right side of the code block, with a light color which gets darker on hover so that it is less obtrusive when overlapping text in block with long lines (#1204). If you want to customize part of the UI to change this default behavior, you can do it using a custom css with bs4_book().
• In bs4_book(), copy button has now a light icon instead of a text with white background (#1192).

• bs4_book() has now some <meta> tags that allows sharing a published book on social media. cover-image, url, title and description set in YAML will be used in index.html and then modified to be adapted per HTML page (#1034).

• repo specification in bs4_book() can now be done in a more flexible way: base url, branch name, subdir and icon can be specify. See ?bookdown::bs4_book() for details (thanks, @maelle, #1036).

• epub_version argument in epub_book() can now be set to epub2 to create EPUB book of version 2. This follows an old change for default behavior in Pandoc 2.0 where the alias epub defaults to epub3 and no more epub2 (thanks, @jtbayly, #1150).

• Theorem and Proof environment can now be used with beamer_presentation2() using fenced Div syntax like this

::: {.theorem #label name="My Theorem"}
Content
:::

However, as beamer defines its own LaTeX theorem environments, bookdown won’t add any definition in preamble as it is doing with pdf_book(). This means user will have to define the ones supported by bookdown and not yet defined by beamer. Special environment from beamer (like fact) needs to be used with usual Custom Blocks syntax. See related issues for examples in their discussions thread (thanks, @XiangyunHuang, #1143, #1145).

This change comes with several small improvements in custom-enviromnent.lua for latex and beamer format, including a new option bookdown.theorem.preamble to opt-out bookdown addition of theorems and proofs definitions in LaTeX preamble. Set it to FALSE if you have conflict with some specific format for example (like #1001).

### MINOR CHANGES

• Updated the jQuery library to v3.x, which is now imported from the R package jquerylib (thanks, @mterente #693, @cooknl #882).

### BUG FIXES

• Removed the requirement for .html filenames to be alphanumeric, which fixes a common error “Automatically generated filenames contain duplicated ones: -” (thanks, @psychelzh #605, @AzureRabbit #902, @carloslederman #1000, Ritsu Kitagawa https://stackoverflow.com/q/60014350/559676, Shrek Tan).

• Fix an issue with bookdown_site() where the comment in site: line key was not supported (thanks, @LDSamson, #1194).

• Figure reference links now point correctly to the top of figures (thanks, @GuillaumeBiessy, #1155).

• When the site field is quoted in index.Rmd’s YAML data (i.e., site: "bookdown::bookdown_site"), bookdown fails to identify the root directory of the book (thanks, @dchiu911, #1160).

• The figure/table labels are no longer duplicated in Word output generated from Pandoc 2.14.1 (thanks, @dewittpe, #1223).

• When a book has multiple authors, the CSS styles for each author were inlined in the <p> tags, and hence are hard to override. Now the class multi-author is applied to each individual author’s <p> tag, and the CSS rules are defined on this class instead (thanks, @robjhyndman, #1170).

• Style change in bs4_book() where code block inside callout blocks will have their background fill the whole width of the bordered block (#1175).

• In bs4_book(), math in footnotes is now rendered (@mine-cetinkaya-rundel, #1026)

• Fix an issue with bs4_book() where text written using Line Block was not found in search (thanks, @dmklotz, #1141).

## CHANGES IN bookdown VERSION 0.22

CRAN release: 2021-04-22

### NEW FEATURES

• New bs4_book() theme - see ?bs4_book for details about this new format (thanks, @hadley, #996).

• render_book() can now take a directory as input, i.e render_book("book_dir"), to render in this directory by using the index.Rmd file if it exists. The default is now to look for input.Rmd is the current working directory. Previously, filename must have been provided (render_book() is now equivalent to render_book("index.Rmd")) (#990).

• hypothesis environment is now supported among Theorems and Proof (thanks, @shirdekel, #1102).

• In _bookdown.yaml, label fields fig, tab and eq can now take a function as ui fields chapter_name and appendix. This function takes the reference number as only argument and must return a character to be used as full label. The default is a string prepended before the reference number. This new feature gives more flexibility to change the default for other language, e.g append the label name after the number. See updated doc about Internationalization(thanks, Tamás Ferenc, #1114)

• Using the ‘Knit’ button now also works with a Rmd file in a sub-directory of the book project (when rmd_subdir is used in _bookdown.yml) (#1122)

• WhatsApp sharing feature has been added for gitbook() using sharing key in config. This enables sharing the bookdown URL in WhatsApp on Mobile and on Desktop (thanks, @prdm0, #1125).

### BUG FIXES

• Adapt CSS in gitbook() and html_book() for correct displaying of <details><summary> content (thanks, @maelle, #971)

• When split_bib = TRUE, references in footnotes are now also correctly relocated in the chapter (thanks, @jimhshen, #952)

• In pdf_book(), toc_bib = TRUE now works with natbib and biblatex as citation_package (thanks, @qifei9, @umarcor, #450).

• CSS dependencies like url('truetype/Spectral-ExtraLight.ttf') (with single quotes) are now correctly identified and moved (thanks, @RLesur, #991).

• fenced_theorems() now correctly transforms implicit label in chunk header to a fenced divs id. (thanks, @enixam, #982)

• References are now correctly relocated with Pandoc 2.11 when split_bib = TRUE in gitbook(). New citation processing in Pandoc 2.11 will also add new classes to the divs, and these are preserved when relocating. This allows for references styling using CSS (#981).

• The new syntax for theorem and proof environments introduced in bookdown requires Pandoc >= 2.3 instead of 2.0 (thanks, @markhymers, #979 #980).

• serve_book() will refresh correctly now when using subdirectories with rmd_subdir (thanks, @shenfei, #834).

• Added the same CSS as in default Pandoc’s template for when a CSL is used (#1045).

• Properly support multiple authors in the gitbook() output format (thanks, @adamvi, #1095).

• No more warnings are thrown when passing several input files to render_book(preview = TRUE) (#1091).

• Correctly remove reference IDs of tables (e.g (#tab:lab)) generated by custom function (like gt::gt()) (#1099).

• In sepia or night mode, the background color during sidebar transition is now correct and no more white (#1100).

• Fix an issue in bs4_book() with encoding on system non-UTF8 by default (#1027).

### MINOR CHANGES

• anchor_sections = TRUE becomes the default for bookdown::gitbook().

## CHANGES IN bookdown VERSION 0.21

CRAN release: 2020-10-13

### NEW FEATURES

• Add the number_sections argument to markdown_document2() and its family. This allows to have now figure references numbered by chapters in these formats, like word_document2() or odt_document2() for example. This argument default to TRUE like html_document2() and pdf_document2(). Set it to number_sections = FALSE to get the same output as previous version without numbered chapters (thanks, @atusy, #756).

• Provided an alternative way to create theorem and proof environments using Pandoc’s fenced Divs. Previously, bookdown supports theorems and proofs in special code chunks like {theorem}. Now you can use the new syntax ::: {.theorem}. You may use the helper function bookdown::fence_theorems() to convert the former syntax to the latter. The main benefit of using fenced Divs is that you can write arbitrary content in a theorem environment (here “theorem” includes other environments such as lemma, corollary, and definition, etc.), such as R code chunks and inline R code, which was not possible previously. Note that this feature is only supported for LaTeX and HTML output formats at the moment. To learn more about the fenced Divs in general, you may read this section in R Markdown Cookbook: https://bookdown.org/yihui/rmarkdown-cookbook/custom-blocks.html (thanks, @tchevri #924, @cderv #940).

### BUG FIXES

• Correctly encode the document title when creating the Twitter sharing link from a bookdown chapter (thanks, @maelle, #934).

• Make sure search_index.json contains valid characters for the JSON format (thanks, @wlandau, #913).

### MAJOR CHANGES

• The --file-scope behavior introduced in bookdown v0.20 is now disabled by default. This is due to broken TOC links for duplicate section names (e.g., “Exercises”; see #909) that have automatically generated identifiers.

• The clean_envir argument of bookdown::render_book() has been deprecated and will be removed in the future (thanks, @jenslaufer, #932).

• The function kindlegen() has been deprecated, since Amazon no longer provides KindleGen. Please consider using bookdown::calibre() instead if you want .mobi output (#973).

### MINOR CHANGES

• Updated documentation for render_book() to make it clearer how options are set for the output_format parameter (thanks, @jonathan-g, #958 #930).

## CHANGES IN bookdown VERSION 0.20

CRAN release: 2020-06-23

### NEW FEATURES

• If delete_merged_file is set to false in _bookdown.yml, the merged (Rmd or md) file will not be deleted after the book is rendered (thanks, ilse pit, https://stackoverflow.com/q/61973608/559676).

• Numeric footnotes duplicated across chapters are now automatically renumbered. This is done by passing the --file-scope argument to pandoc (and having it operate on split out individual chapters of the target .md file rather than a combined file). This behavior can be toggled off by setting options(bookdown.render.file_scope = FALSE).

### BUG FIXES

• Fixed a JS issue in gitbook when it is used with jQuery 3.x (thanks, @afkegel, #895).

### MINOR CHANGES

• Removed the encoding argument from bookdown::render_book(). This argument has always been ignored in bookdown.

## CHANGES IN bookdown VERSION 0.19

CRAN release: 2020-05-15

### BUG FIXES

• Multiline footnotes are now correctly rendered in HTML output (thanks, @jtbayly, @cderv, #876).

• Text references do not work for theorem environments (thanks, @ssp3nc3r, rstudio/tufte#75).

• When both rmd_subdir and rmd_files are provided in the config file _bookdown.yml, only the files specified in rmd_files are now selected in addition to files under rmd_subdir. In the previous version, all files under the root directory are selected (thanks, @Gnossos #885, @cderv #886).

• When rmd_subdir is provided in _bookdown.yml, the subdirectories were always alphabetically ordered instead of following the order of elements in rmd_subdir (thanks, @Rothdyt, #736).

### MAJOR CHANGES

• Files with a leading _ in their names are always ignored, even if they are specified in rmd_files in _bookdown.yml. Such files under subdirectories are also always ignored (#886).

## CHANGES IN bookdown VERSION 0.18

CRAN release: 2020-03-05

### NEW FEATURES

• Added an output format context_document2, based on the newly developed rmarkdown::context_document (see rstudio/rmarkdown#1713, rstudio/rmarkdown#1715, and rstudio/rmarkdown#1725; thanks @jooyoungseo, @atusy, and @RLesur).

### BUG FIXES

• render_book() works correctly with output_dir = "." now (thanks, @julianre, @cderv, #857).

• Cross-referencing works correctly now with gitbook when using split_by: section or split_by: section+number (thanks, @ThierryO, @cderv, #787).

• When using the Knit-and-Merge approach to compile a book (new_session: true in _bookdown.yml) and the fields before_chapter_script and/or after_chapter_script are configured in _bookdown.yml, the original Rmd files are no longer touched (thanks, @clauswilke #405 and @bob-carpenter https://stackoverflow.com/q/50554196/559676), and the scripts specified in before/after_chapter_script are no longer inserted into the Rmd files (they are read and evaluated separately), so the line numbers will be correct in case of knitr errors (thanks, @arencambre, #852).

## CHANGES IN bookdown VERSION 0.17

CRAN release: 2020-01-11

### NEW FEATURES

• Added an output format github_document2, which is a wrapper function based on markdown_document2 using rmarkdown::github_document as the base format (thanks, @jooyoungseo, #831).

### BUG FIXES

• Fixed cross-reference issues with Pandoc 2.9+. Note that Pandoc 2.8 is not supported since it had a fairly short lifespan, but Pandoc below v2.8 or above v2.9 is still supported (thanks, @N0rbert @RLesur, #832; @jooyoungseo #845).

• For output formats like pdf_book, unused arguments passed to base_format will be discarded (thanks, @jooyoungseo, #790).

• For the sake of backward-compatibility, prevent the commands \frontmatter, \mainmatter, and \backmatter from being automatically added to the LaTeX output when the Pandoc version is higher than 2.7, because bookdown users may have added these commands by themselves (thanks, @remlapmot, rstudio/rmarkdown#1721).

• Fixed the issues yihui/bookdown-chinese#29 and yihui/bookdown-chinese#30. Such issues can occur on Windows when there are multibyte characters in the section headers, and users will run into the error “Error in file.exists(f): file name conversion problem - name too long?” (thanks, @kongdd @JiaxiangBU @gaospecial and other users who reported the same issue such as https://twitter.com/matsuchiy/status/1186653559405727744 and https://d.cosx.org/d/420961).

### MINOR CHANGES

• The default value of base_format in the markdown_document2 format is rmarkdown::md_document now. Previously the default value is missing.

## CHANGES IN bookdown VERSION 0.16

CRAN release: 2019-11-22

### NEW FEATURES

• You can also add a “view” button on the GitBook toolbar, similar to the “edit” and “history” buttons, which shows the page’s .Rmd source file on GitHub. Unlike “edit”, “view” does not require the reader to login to GitHub and fork the repo (thanks, @jtr13, #806).

• For gitbook output, the font setting button can be removed via fontsettings: false in the config option. Similarly, the info button can be removed by info: false in config (thanks, @mnazarov, #788).

• It is possible to customize the prefixes of appendix titles in gitbook output now (the default is still A, B, C, …, and now you can change them to something like Appendix A, Appendix B, …); see the documentation at https://bookdown.org/yihui/bookdown/internationalization.html (thanks, @WerthPADOH, #783).

• Added html_fragment2, html_notebook2, html_vignette2, ioslides_presentation2, slidy_presentation2, and beamer_presentation2 for cross-referencing capabilities on top of rmarkdown output formats (thanks, @jooyoungseo, #789 #823).

### BUG FIXES

• For the gitbook output format, disabling the sharing menu or buttons works again (thanks, @lwjohnst86, #812).

• For the gitbook output format, toc collapsed by section now works with accents in chapter titles (thanks, @glimmerphoenix, @cderv, #819)

• For output formats word_document2, powerpoint_presentation2, and odt_document2,  is no longer added to equation environments when they are inside fenced code blocks (thanks, @N0rbert, #814).

## CHANGES IN bookdown VERSION 0.15

CRAN release: 2019-11-12

### BUG FIXES

• Sharing to Facebook and Twitter is possible again. Google+ sharing has been disabled (with a warning) as this service no longer exists (thanks, @cderv, #802).

• When using Pandoc 2.7.3 or later, footnotes are now placed again at the end of each chapter (#798, #801, thanks @cderv).

• gitbook toolbar is not missing any more when rendering books with Pandoc 2.x and using self_contained = TRUE (thanks, @Pindar777, @RLesur, @cderv, #739).

## CHANGES IN bookdown VERSION 0.14

CRAN release: 2019-10-01

### BUG FIXES

• Images specified in toc: before: of the gitbook format are not copied to the output directory (thanks, @dcossyleon, #763).

## CHANGES IN bookdown VERSION 0.13

CRAN release: 2019-08-21

### NEW FEATURES

• Added odt_document2 and powerpoint_presentation2 (thanks, @atusy, #742).

• Added markdown_document2 which enables to use cross references in an arbitrary format specified in base_format argument (e.g., markdown_document2(base_format = prettydoc::html_pretty)) (thanks, @atusy, #742).

## CHANGES IN bookdown VERSION 0.12

CRAN release: 2019-07-11

### MINOR CHANGES

• Reverted #706 and removed the clean_highlight_tags argument in html_document2(); bookdown will no longer clean up the HTML tags of the syntax-highlighted code blocks.

## CHANGES IN bookdown VERSION 0.11

CRAN release: 2019-05-28

## CHANGES IN bookdown VERSION 0.10

CRAN release: 2019-05-10

### NEW FEATURES

• Added an argument clean_highlight_tags to html_document2() (thanks, @atusy, #706).

• For HTML output formats such as gitbook, the abstract title (if the abstract is provided) can be customized via the field abstract-title in the YAML frontmatter (thanks, @XiangyunHuang, #715).

### BUG FIXES

• Split reference sections in gitbook ignored the sorting definition of the citation style (thanks @GegznaV #661, @crsh #674).

• For the gitbook output format, the content doesn’t get the focus when the page is loaded, which makes it fail to respond to keystrokes such as PageUp/PageDown/Up/Down (thanks, @darshanbaral #691, @aronatkins #699).

• For the gitbook output format, when searching for keywords in code blocks, the automatic scroll to keywords doesn’t work (thanks, @colearendt, #700).

• The search keyword no longer persists across page loads for different books in the gitbook format (thanks, @aronatkins, #695).

• The keybindings Up and Down (or Enter) in the search input of the gitbook output format work across all pages now; previously they only work on the current page (thanks, @dsblank, #657).

• When performing searching, the gitbook sidebar will only display relevant TOC items that actually take users to the HTML pages containing the search keyword. Previously, some TOC items do not really take users to the search destination but an anchor on a page instead, which can be confusing (thanks, @aronatkins, #696).

• Hyphenated words will be correctly highlighted in the search results now if spaces are used in the search keyword instead of dashes, e.g., you can search for hand-off using the keyword hand off (thanks, @aronatkins, #701).

• When rmd_files is configured in _bookdown.yml, render_book() will fail if the output format is not HTML or LaTeX (thanks, Ladislas Nalborczyk, https://stackoverflow.com/q/56061122/559676).

• The colon after figure/table numbers is missing in Word and EPUB output (thanks, @upton9265, #618).

• Multiple labels on the same line are allowed for Word output (thanks, @mdlincoln @h-k-kan @brooksambrose, #538).

### MINOR CHANGES

• Added alt/hover text to icons on the gitbook toolbar (thanks, @aronatkins, #698).

• Added an Information button to the gitbook toolbar to show the keybindings that are otherwise difficult for users to discover without reading the bookdown book (thanks, @aronatkins, #697).

• Added information about the keybindings Enter/Up/Down to the placeholder text and tooltip of the search input in gitbook output (thanks, @pyltime, #660).

## CHANGES IN bookdown VERSION 0.9

CRAN release: 2018-12-21

### BUG FIXES

• The tags for OpenGraph titles in HTML output were not properly closed.

## CHANGES IN bookdown VERSION 0.8

CRAN release: 2018-12-03

### NEW FEATURES

• Added Conjecture to the list of theorem environments.

• In addition to rmd_subdir: true, which searches all subdirectories, you can now provide a list of subdirectories to be recursively searched (#242).

• Added an argument template to gitbook() and epub_book() (thanks, @ThierryO, #570).

• Added an argument table_css to gitbook() to allow customized css for tables. (thanks, @haozhu233, #642)

• You can also add a “history” button on the Gitbook toolbar, which is similar to the “edit” button, but shows the GIT history of a source file instead (thanks, @maelle #638, @noamross, #639).

• Added a quiet argument to serve_book(), so that users can suppress stdout with bookdown::serve_book(quiet = TRUE) (thanks, @hammer, #633).

• For HTML output, the title of the current chapter or section will be added to the page title (in the <title> tag). This will give readers more information when reading the results from search engines or Twitter cards. Previously, all pages would have identical titles (thanks, @benwhalley and @batpigandme, #544).

### BUG FIXES

• HTML output formats such as gitbook and html_document2 won’t work when only unnumbered parts (i.e., # (PART\*)) are used (thanks, @tjmahr, #575).

• Previously the rmd_files parameter in _bookdown.yml would override rmd_subdir, but now both parameters can be used simultaneously (thanks, @ellisvalentiner, #600).

• Resources with URL encoded special characters are now correctly copied to the output directory (thanks, @AshesITR, #622).

• serve_book() can now be used without error when rstudioapi is installed but RStudio is not being used (thanks, @jimhester, #637).

• Text references via (ref:label) for bookdown::pdf_document() doesn’t always work (thanks, @brendanf, #616).

## CHANGES IN bookdown VERSION 0.7

CRAN release: 2018-02-18

### MAJOR CHANGES

• The label prefix for Example blocks must be exm: (ex: is no longer supported).

## CHANGES IN bookdown VERSION 0.6

CRAN release: 2018-01-25

### NEW FEATURES

• Added an argument config_file to render_book() so that one can specify a custom config file; the default config file is still _bookdown.yml (thanks, @stephlocke, #465).

• Added a global option bookdown.preview.cutoff (defaults to 30) for the preview mode render_book(preview = TRUE): when the number of lines of a chapter is smaller or equal to this number, the full chapter is included in the preview; otherwise, only the section titles are extracted from the chapter for preview.

## CHANGES IN bookdown VERSION 0.5

CRAN release: 2017-08-20

### NEW FEATURES

• Added support for two more environments: Exercises and Solutions (thanks, @dshuman1, #423).

• If the Rmd file merged from all chapters exists and you are sure it can be safely deleted, you can set an option delete_merged_file to true in _bookdown.yml (thanks, @dmenne, #442).

### BUG FIXES

• The book cannot be properly rendered when the option book_filename in _bookdown.yml contains a dot (thanks, @pinusm, #410).

• Proof and Remark blocks do not work well for EPUB output (thanks, @mamaciasq, #443).

• When split_by = 'section' for the gitbook output format, navigation buttons are missing on the page before the appendix (thanks, @dataopt, #409).

### MINOR CHANGES

• The label prefix for Example blocks was changed from ex: to exm:.

## CHANGES IN bookdown VERSION 0.4

CRAN release: 2017-05-20

### NEW FEATURES

• Added special syntax for unnumbered part headers: # (PART\*). Numbered parts should be written after # (PART) as before (thanks, @brooksambrose, https://stackoverflow.com/q/43688902/559676).

• The gitbook output format also supports abstract in YAML now (thanks, @maxheld83, #311).

• For the gitbook output format, the downloads option in config supports rmd now (e.g. download: ["pdf", "epub", "rmd"]) if the edit link has been specified and is a link to Github (thanks, @coatless, #330).

• You can set the global R option bookdown.post.latex via options() to be a function to post-process the LaTeX output of the pdf_book format; see ?bookdown::pdf_book for details (thanks, @nicksolomon, #373).

### BUG FIXES

• The HTML output file is not moved to the output directory when split_by = 'none' in bookdown::gitbook or bookdown::html_book (https://stackoverflow.com/q/40976073/559676).

• The YAML option includes: before_body works correctly for gitbook output now (thanks, @benmarwick, #267).

• Theorem environments are not defined for LaTeX output unless a theorem block is present (thanks, @JeffreyRacine, #291).

• For remark and proof blocks, the chunk option name did not work correctly for non-LaTeX output (thanks, @ugroempi, #347).

• Some text references do not work for HTML and Word output (thanks, @ugroempi, #363).

• The option chapter_name in _bookdown.yml does not work when it is specified as a function (thanks, @tzerk, 0c05c3828be).

• External assets such as fonts/css files should never be wiped when rendering a book to HTML (thanks, @nicholaelaw, #398).

### MINOR CHANGES

• The daemon argument was removed from serve_book(), but you can still pass it to servr::httw() via the ... argument.

• Added a small space (padding) to the right of section numbers in gitbook output, so that the section numbers are better separated from the titles (thanks, @aronatkins, #367).

## CHANGES IN bookdown VERSION 0.3

CRAN release: 2016-11-28

### NEW FEATURES

• Added a Github button in the group of sharing buttons on the toolbar. By default, this button is not displayed. You have to set github: yes under sharing in the gitbook configurations (https://bookdown.org/yihui/bookdown/html.html) and specify your Github repo using the top-level option github-repo in the YAML metadata of index.Rmd, e.g. github-repo: rstudio/bookdown.

• The appendix heading will be preserved in bookdown::html_document2 output, e.g. if you have # (APPENDIX) Appendix {-} in your document, you will see the heading Appendix in the output. Previously it was removed.

• Parts in HTML output are also be numbered using roman numerals like LaTeX/PDF output.

### BUG FIXES

• Wrong part titles were inserted to the table of contents of PDF output (thanks, @florisvdh, #243).

• Cross-references for appendices in html_document2 output did not work (thanks, @florisvdh, #245).

• Part titles were not correctly processed when they were longer than 20 characters in PDF output (thanks, @florisvdh, #246).

## CHANGES IN bookdown VERSION 0.2

CRAN release: 2016-11-12

### NEW FEATURES

• Added arguments toc_unnumberred, toc_appendix, toc_bib, and quote_footer to pdf_book().

• Added support for cross-referencing equations in multi-page HTML output and EPUB; see https://bookdown.org/yihui/bookdown/ for the syntax (thanks, @deleeuw, #85).

• Rmd files can live in subdirectories if you use the Merge-and-Knit approach (the default), and they will be found if the configuration option rmd_subdir is true in _bookdown.yml (thanks, @leobuchignani, #205).

### MAJOR CHANGES

• The force_knit argument of render_book() was removed (to avoid confusion when switching output formats).

### BUG FIXES

• Figures are not correctly numbered in Word output using the bookdown::word_document2() format (thanks, @byzheng, #158).

• For the “Knit and Merge” approach (new_session: yes in _bookdown.yml), certain parts like figures may not show up when switching from one output format to another (e.g. from HTML to LaTeX).

• The rmd_files option in _bookdown.yml does not work when it is a list of html and latex options (thanks, @ismayc, #177).

• Math expressions does not appear in the table of contents when the output format is gitbook (thanks, @philomonk, #204).

• Footnotes of multiple paragraphs are not displayed on the current page (thanks, @axitdn, #234).

• The output format pdf_document2()` also works with articles now when an R Markdown document contains bookdown-specific headers, such as parts or appendix headers (https://stackoverflow.com/q/40529798/559676).

## CHANGES IN bookdown VERSION 0.1

CRAN release: 2016-07-13

### NEW FEATURES

• Initial CRAN release.