[couchdb] 01/01: fix(3517): super-simplistic fix to avoid costly AST transforms when they are not needed

[jan]

This is an automated email from the ASF dual-hosted git repository.

jan pushed a commit to branch fix/3517-part7
in repository https://gitbox.apache.org/repos/asf/couchdb.git

commit 05628e891b5145c09e429eb79a21631cddf63c43
Author: Jan Lehnardt <j...@apache.org>
AuthorDate: Tue Dec 6 12:50:15 2022 +0100

    fix(3517): super-simplistic fix to avoid costly AST transforms when they 
are not needed
---
 share/server/60/rewrite_fun.js | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/share/server/60/rewrite_fun.js b/share/server/60/rewrite_fun.js
index 1b27a9d14..dc273f012 100644
--- a/share/server/60/rewrite_fun.js
+++ b/share/server/60/rewrite_fun.js
@@ -16,6 +16,16 @@
 //  https://github.com/dmunch/couch-chakra/blob/master/js/normalizeFunction.js
 
 function rewriteFunInt(fun) {
+
+    // low-key check if we actually have to do an AST transform
+    // most users’ functions start with the keyword function
+    // and if that’s the case, we bypass the AST transform
+    // if users need an AST transform anyway, they can change this to
+    // ` function` (add a leading whitespace).
+    if (fun.substr(0, 'function'.length-1) === 'function') {
+        return fun
+    }
+
     const ast = esprima.parse(fun);
     let idx = ast.body.length - 1;
     let decl = {};