fix(functions): reset RegExp.lastIndex to zero when using cached RegE…

…xp objects (#2079)
stoplightio · Mar 7, 2022 · 4839527 · 4839527
1 parent dda11ef
commit 4839527
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diff --git a/packages/functions/src/__tests__/pattern.test.ts b/packages/functions/src/__tests__/pattern.test.ts
@@ -18,6 +18,12 @@ describe('Core Functions / Pattern', () => {
       expect(await runPattern('aBc', { match: '/[abc]+/im' })).toEqual([]);
     });
 
+    it('should return same results when given a global (g) marker (pattern cache usecase)', async () => {
+      expect(await runPattern('abc', { match: '/[abc]+/gi' })).toEqual([]);
+      expect(await runPattern('abc', { match: '/[abc]+/gi' })).toEqual([]);
+      expect(await runPattern('abc', { match: '/[abc]+/gi' })).toEqual([]);
+    });
+
     it('given string regex containing invalid flags, should throw an exception', async () => {
       await expect(runPattern('aBc', { match: '/[abc]+/invalid' })).rejects.toThrow(
         "Invalid flags supplied to RegExp constructor 'invalid'",

diff --git a/packages/functions/src/pattern.ts b/packages/functions/src/pattern.ts
@@ -27,6 +27,7 @@ const cache = new Map<string, RegExp>();
 function getFromCache(pattern: string): RegExp {
   const existingPattern = cache.get(pattern);
   if (existingPattern !== void 0) {
+    existingPattern.lastIndex = 0;
     return existingPattern;
   }