From 3200259430b1d3be178f5943d9ba0f0b59307d34 Mon Sep 17 00:00:00 2001
From: Geoffrey Booth <geoffrey.booth@disney.com>
Date: Mon, 14 Nov 2016 17:33:20 -0800
Subject: [PATCH] Block inline JavaScript can end with an escaped backtick
 character

---
 lib/coffee-script/lexer.js      | 18 ++++++------------
 src/lexer.coffee                | 15 +++++----------
 test/javascript_literals.coffee |  7 +++++++
 3 files changed, 18 insertions(+), 22 deletions(-)

diff --git a/lib/coffee-script/lexer.js b/lib/coffee-script/lexer.js
index c3535458a2..831f8cf161 100644
--- a/lib/coffee-script/lexer.js
+++ b/lib/coffee-script/lexer.js
@@ -336,21 +336,15 @@
     };
 
     Lexer.prototype.jsToken = function() {
-      var here, js, length, match, script;
+      var js, match, script;
       if (!(this.chunk.charAt(0) === '`' && (match = JSTOKEN.exec(this.chunk)))) {
         return 0;
       }
-      js = match[0], here = match[1];
-      if (here != null) {
-        script = here;
-        length = here.length + 6;
-      } else {
-        script = js.slice(1, -1);
-        length = js.length;
-      }
+      js = match[0];
+      script = js.slice(0, 3) === '```' ? js.slice(3, -3) : js.slice(1, -1);
       script = script.replace(/\\`/g, '`');
-      this.token('JS', script, 0, length);
-      return length;
+      this.token('JS', script, 0, js.length);
+      return js.length;
     };
 
     Lexer.prototype.regexToken = function() {
@@ -1018,7 +1012,7 @@
 
   MULTI_DENT = /^(?:\n[^\n\S]*)+/;
 
-  JSTOKEN = /^```([\s\S]*?)```|^`[^\\`]*(?:\\.[^\\`]*)*`/;
+  JSTOKEN = /^```([\s\S]*?)(?:\\`(```)|```)|^`[^\\`]*(?:\\.[^\\`]*)*`/;
 
   STRING_START = /^(?:'''|"""|'|")/;
 
diff --git a/src/lexer.coffee b/src/lexer.coffee
index 4c17c1b3ed..d55bcc4ab4 100644
--- a/src/lexer.coffee
+++ b/src/lexer.coffee
@@ -293,16 +293,11 @@ exports.Lexer = class Lexer
   # Matches JavaScript interpolated directly into the source via backticks.
   jsToken: ->
     return 0 unless @chunk.charAt(0) is '`' and match = JSTOKEN.exec @chunk
-    [js, here] = match
-    if here?
-      script = here
-      length = here.length + 6 # 6 is the length of the six ` characters
-    else
-      script = js[1...-1]
-      length = js.length
+    [js] = match
+    script = if js[0..2] is '```' then js[3...-3] else js[1...-1]
     script = script.replace /\\`/g, '`' # Convert escaped backticks to backticks
-    @token 'JS', script, 0, length
-    length
+    @token 'JS', script, 0, js.length
+    js.length
 
   # Matches regular expression literals, as well as multiline extended ones.
   # Lexing regular expressions is difficult to distinguish from division, so we
@@ -908,7 +903,7 @@ CODE       = /^[-=]>/
 
 MULTI_DENT = /^(?:\n[^\n\S]*)+/
 
-JSTOKEN    = /^```([\s\S]*?)```|^`[^\\`]*(?:\\.[^\\`]*)*`/
+JSTOKEN    = /^```([\s\S]*?)(?:\\`(```)|```)|^`[^\\`]*(?:\\.[^\\`]*)*`/
 
 # String-matching-regexes.
 STRING_START   = /^(?:'''|"""|'|")/
diff --git a/test/javascript_literals.coffee b/test/javascript_literals.coffee
index 154443bf43..c6a95ce86e 100644
--- a/test/javascript_literals.coffee
+++ b/test/javascript_literals.coffee
@@ -38,3 +38,10 @@ test "block inline JavaScript containing backticks", ->
   eq a + c, 45
   eq b, 'foo bar'
   eq d, 'foo`bar`'
+
+test "block JavaScript can end with an escaped backtick character", ->
+  ```var a = \`hello\````
+  ```
+  var b = \`world${'!'}\````
+  eq a, 'hello'
+  eq b, 'world!'