XRegExp.escape: Escape # and , in way that works with ES6 flag u (#323)

src/xregexp.js

@@ -796,18 +796,16 @@ XRegExp.cache.flush = (cacheName) => {
 // - `[()*+?.$|` - context: default
 // - `]` - context: default with flag u or if forming the end of a character class
 // - `{}` - context: default with flag u or if part of a valid/complete quantifier pattern
-// - `,` - context: default if in a position that causes an unescaped `{` to turn into a
-//   quantifier. E.g. /^a{1\,2}$/ matches 'a{1,2}', but /^a{1,2}$/ matches 'a' or 'aa'.
-// - `#` and whitespace - context: default with flag x
+// - `,` - context: default if in a position that causes an unescaped `{` to turn into a quantifier.
+//   Ex: `/^a{1\,2}$/` matches `'a{1,2}'`, but `/^a{1,2}$/` matches `'a'` or `'aa'`
+// - `#` and <whitespace> - context: default with flag x
 // - `^` - context: default, and context: class if it's the first character in the class
 // - `-` - context: class if part of a valid character class range
 XRegExp.escape = (str) => String(nullThrows(str)).
     // Escape most special chars with a backslash
-    replace(/[\\\[\]{}()*+?.,^$|#]/g, '\\$&').
-    // Convert whitespace to \uNNNN since it can't be escaped when used with ES6 flag `u`
-    replace(/\s/g, (match) => `\\u${pad4(hex(match.charCodeAt(0)))}`).
-    // Convert hyphen to \x2D since it can't be escaped when used with ES6 flag `u`
-    replace(/-/g, '\\x2D');
+    replace(/[\\\[\]{}()*+?.^$|]/g, '\\$&').
+    // Convert to \uNNNN for special chars that can't be escaped when used with ES6 flag `u`
+    replace(/[\s#\-,]/g, (match) => `\\u${pad4(hex(match.charCodeAt(0)))}`);
 
 /**
  * Executes a regex search in a specified string. Returns a match array or `null`. If the provided

tests/spec/s-xregexp-methods.js

@@ -230,7 +230,7 @@ describe('XRegExp.escape()', function() {
     });
 
     it('should handle escaping with ES6 flag u', function() {
-        expect(new RegExp('^' + XRegExp.escape(' - ') + '$', hasNativeU ? 'u' : '').test(' - ')).toBe(true);
+        expect(new RegExp('^' + XRegExp.escape(' \n-,#') + '$', hasNativeU ? 'u' : '').test(' \n-,#')).toBe(true);
     });
 
     it('should not escape nonmetacharacters', function() {