Safeguard against trailing slash in purge matches (#2364)

Author: adamwathan

__tests__/fixtures/purge-example.html

@@ -37,3 +37,8 @@
     %samp.font-mono{:data-foo => "bar"}= output
     .col-span-4[aria-hidden=true]
     .tracking-tight#headline
+
+<!-- JSON -->
+{
+  "helloThere": "Hello there, <span class=\"whitespace-no-wrap\">Mr. Jones</span>"
+}

__tests__/purgeUnusedStyles.test.js

@@ -90,7 +90,7 @@ function assertPurged(result) {
   expect(result.css).toContain('.font-mono')
   expect(result.css).toContain('.col-span-4')
   expect(result.css).toContain('.tracking-tight')
-  expect(result.css).toContain('.tracking-tight')
+  expect(result.css).toContain('.whitespace-no-wrap')
 }
 
 test('purges unused classes', () => {

src/lib/purgeUnusedStyles.js

@@ -112,14 +112,17 @@ export default function purgeUnusedUtilities(config, configChanged) {
       defaultExtractor: content => {
         // Capture as liberally as possible, including things like `h-(screen-1.5)`
         const broadMatches = content.match(/[^<>"'`\s]*[^<>"'`\s:]/g) || []
+        const broadMatchesWithoutTrailingSlash = broadMatches.map(match => _.trimEnd(match, '\\'))
 
         // Capture classes within other delimiters like .block(class="w-1/2") in Pug
         const innerMatches = content.match(/[^<>"'`\s.(){}[\]#=%]*[^<>"'`\s.(){}[\]#=%:]/g) || []
 
+        const matches = broadMatches.concat(broadMatchesWithoutTrailingSlash).concat(innerMatches)
+
         if (_.get(config, 'purge.preserveHtmlElements', true)) {
-          return [...htmlTags].concat(broadMatches).concat(innerMatches)
+          return [...htmlTags].concat(matches)
         } else {
-          return broadMatches.concat(innerMatches)
+          return matches
         }
       },
       ...config.purge.options,