fix #1522: use the first <title> if there are multiple

yihui · yihui · commit d520023b6690 · 2026-05-05T18:57:52.000-05:00
diff --git a/DESCRIPTION b/DESCRIPTION
@@ -1,7 +1,7 @@
 Package: bookdown
 Type: Package
 Title: Authoring Books and Technical Documents with R Markdown
-Version: 0.46.3
+Version: 0.46.4
 Authors@R: c(
     person("Yihui", "Xie", role = c("aut", "cre"), email = "xie@yihui.name", comment = c(ORCID = "0000-0003-0645-5666")),
     person("Christophe", "Dervieux", , "cderv@posit.co", role = c("ctb"),
diff --git a/NEWS.md b/NEWS.md
@@ -1,5 +1,6 @@
 # CHANGES IN bookdown VERSION 0.47
 
+- Fixed the bug that `prepend_chapter_title()` errors with "the condition has length > 1" when the page `<head>` contains more than one `<title>` tag (thanks, @samperman, #1522).
 
 # CHANGES IN bookdown VERSION 0.46
 
diff --git a/R/html.R b/R/html.R
@@ -1226,6 +1226,7 @@ restore_math_labels = function(x) {
 prepend_chapter_title = function(head, body) {
   r1 = '(.*?<title>)(.+?)(</title>.*)'
   if (length(i <- grep(r1, head)) == 0) return(head)
+  i = i[1]
   body = paste(body, collapse = ' ')
   r2 = '.*?<h[0-6][^>]*>(.+?)</h[0-6]>.*'
   if (!grepl(r2, body)) return(head)

Original file line number	Diff line number	Diff line change
`@@ -1,5 +1,6 @@`
`1`	`1`	`# CHANGES IN bookdown VERSION 0.47`
`2`	`2`
	`3`	+- Fixed the bug that `prepend_chapter_title()` errors with "the condition has length > 1" when the page `<head>` contains more than one `<title>` tag (thanks, @samperman, #1522).
`3`	`4`
`4`	`5`	`# CHANGES IN bookdown VERSION 0.46`
`5`	`6`