Cache keyword regexps

Closes #1233
acornjs · Aug 11, 2023 · c5b8cae · c5b8cae
1 parent 38b7af4
commit c5b8cae
Showing 1 changed file with 3 additions and 1 deletion.
diff --git a/acorn/src/util.js b/acorn/src/util.js
@@ -8,8 +8,10 @@ export const isArray = Array.isArray || ((obj) => (
   toString.call(obj) === "[object Array]"
 ))
 
+const regexpCache = Object.create(null)
+
 export function wordsRegexp(words) {
-  return new RegExp("^(?:" + words.replace(/ /g, "|") + ")$")
+  return regexpCache[words] || (regexpCache[words] = new RegExp("^(?:" + words.replace(/ /g, "|") + ")$"))
 }
 
 export function codePointToString(code) {