From a8806546e38ca10ffd3db559dff1abc2dc67e5ad Mon Sep 17 00:00:00 2001
From: Rich Trott <rtrott@gmail.com>
Date: Mon, 10 May 2021 22:12:33 -0700
Subject: [PATCH] fix: remove replacement char from start and end in strict
 mode

In addition to fixing the bug, this also removes dynamically generated
regular expresions which could result in unexpected behavior when the
replacement character is a special character in regulard expressions,
such as `.`.

Refs: https://github.com/simov/slugify/issues/112#issuecomment-836365587
---
 slugify.js      | 25 +++++++++++--------------
 test/slugify.js |  4 ++++
 2 files changed, 15 insertions(+), 14 deletions(-)

diff --git a/slugify.js b/slugify.js
index 56f4b8f..277111b 100644
--- a/slugify.js
+++ b/slugify.js
@@ -34,23 +34,20 @@
         return result + (locale[ch] || charMap[ch] ||  (ch === replacement ? ' ' : ch))
           // remove not allowed characters
           .replace(options.remove || /[^\w\s$*_+~.()'"!\-:@]+/g, '')
-      }, '')
-      // trim leading/trailing spaces
-      .trim()
-      // convert spaces to replacement character
-      // also remove duplicates of the replacement character
-      .replace(/\s+/g, replacement)
+      }, '');
 
-    if (options.lower) {
-      slug = slug.toLowerCase()
+    if (options.strict) {
+      slug = slug.replace(/[^A-Za-z0-9\s]/g, '');
     }
 
-    if (options.strict) {
-      // remove anything besides letters, numbers, and the replacement char
-      slug = slug
-        .replace(new RegExp('[^a-zA-Z0-9' + replacement + ']', 'g'), '')
-        // remove duplicates of the replacement character
-        .replace(new RegExp('[\\s' + replacement + ']+', 'g'), replacement)
+    // Remove leading/trailing spaces, then replace all other spaces with
+    // replacement character, treating multiple consecutive spaces as a single
+    // space.
+    slug = slug.trim()
+      .replace(/\s+/g, replacement);
+
+    if (options.lower) {
+      slug = slug.toLowerCase()
     }
 
     return slug
diff --git a/test/slugify.js b/test/slugify.js
index 1b6a98c..32a8db0 100644
--- a/test/slugify.js
+++ b/test/slugify.js
@@ -257,4 +257,8 @@ describe('slugify', () => {
   it('replaces leading and trailing replacement chars', () => {
     t.equal(slugify('-Come on, fhqwhgads-'), 'Come-on-fhqwhgads')
   })
+
+  it('replaces leading and trailing replacement chars in strict mode', () => {
+    t.equal(slugify('! Come on, fhqwhgads !', { strict: true }), 'Come-on-fhqwhgads')
+  })
 })