jashkenas · STRd6 · Nov 26, 2022 · Nov 26, 2022 · Nov 26, 2022 · Nov 27, 2022
diff --git a/docs/v2/browser-compiler-legacy/coffeescript.js b/docs/v2/browser-compiler-legacy/coffeescript.js
diff --git a/docs/v2/browser-compiler-modern/coffeescript.js b/docs/v2/browser-compiler-modern/coffeescript.js
diff --git a/docs/v2/test.html b/docs/v2/test.html
@@ -26000,7 +26000,7 @@ <h1>CoffeeScript Test Suite</h1>
 # TODO: improve heregex interpolation tests
 
 test "heregex interpolation", ->
-  eq /\\#{}\\"/ + '', ///
+  eq /\#{}\\"/ + '', ///
    #{
      "#{ '\\' }" # normal comment
    }

diff --git a/lib/coffeescript-browser-compiler-legacy/coffeescript.js b/lib/coffeescript-browser-compiler-legacy/coffeescript.js
diff --git a/lib/coffeescript-browser-compiler-modern/coffeescript.js b/lib/coffeescript-browser-compiler-modern/coffeescript.js
diff --git a/lib/coffeescript/lexer.js b/lib/coffeescript/lexer.js
diff --git a/lib/coffeescript/nodes.js b/lib/coffeescript/nodes.js
diff --git a/src/lexer.coffee b/src/lexer.coffee
@@ -1341,10 +1341,10 @@ HERE_JSTOKEN = ///^ ```     ((?: [^`\\] | \\[\s\S] | `(?!``) )*) ``` ///
 # String-matching-regexes.
 STRING_START   = /^(?:'''|"""|'|")/
 
-STRING_SINGLE  = /// ^(?: [^\\']  | \\[\s\S]                      )* ///
-STRING_DOUBLE  = /// ^(?: [^\\"#] | \\[\s\S] |           \#(?!\{) )* ///
-HEREDOC_SINGLE = /// ^(?: [^\\']  | \\[\s\S] | '(?!'')            )* ///
-HEREDOC_DOUBLE = /// ^(?: [^\\"#] | \\[\s\S] | "(?!"") | \#(?!\{) )* ///
+STRING_SINGLE  = /// ^(?: [^\\']   | \\[\s\S]                      )* ///
+STRING_DOUBLE  = /// ^(?: [^\\"\#] | \\[\s\S] |           \#(?!\{) )* ///
+HEREDOC_SINGLE = /// ^(?: [^\\']   | \\[\s\S] | '(?!'')            )* ///
+HEREDOC_DOUBLE = /// ^(?: [^\\"\#] | \\[\s\S] | "(?!"") | \#(?!\{) )* ///
 
 INSIDE_JSX = /// ^(?:
     [^
@@ -1376,15 +1376,15 @@ VALID_FLAGS  = /^(?!.*(.).*\1)[gimsuy]*$/
 HEREGEX      = /// ^
   (?:
       # Match any character, except those that need special handling below.
-      [^\\/#\s]
+      [^\\/\#\s]
       # Match `\` followed by any character.
     | \\[\s\S]
       # Match any `/` except `///`.
     | /(?!//)
       # Match `#` which is not part of interpolation, e.g. `#{}`.
     | \#(?!\{)
       # Comments consume everything until the end of the line, including `///`.
-    | \s+(?:#(?!\{).*)?
+    | \s*(?:\#(?!\{).*)?
   )*
 ///
 

diff --git a/src/nodes.coffee b/src/nodes.coffee
@@ -5782,8 +5782,8 @@ STRING_OMIT    = ///
 ///g
 HEREGEX_OMIT = ///
     ((?:\\\\)+)     # Consume (and preserve) an even number of backslashes.
-  | \\(\s)          # Preserve escaped whitespace.
-  | \s+(?:#.*)?     # Remove whitespace and comments.
+  | \\(\s|\#)       # Preserve escaped whitespace and '#'.
+  | \s*(?:\#.*)?    # Remove whitespace and comments.
 ///g
 
 # Helper Functions

diff --git a/test/interpolation.coffee b/test/interpolation.coffee
@@ -146,7 +146,7 @@ ok /^a[\s\S]+b$/.test "a#{ (x) -> x %% 2 }b"
 # TODO: improve heregex interpolation tests
 
 test "heregex interpolation", ->
-  eq /\\#{}\\"/ + '', ///
+  eq /\#{}\\"/ + '', ///
    #{
      "#{ '\\' }" # normal comment
    }