From eb9561878b2f272e5f7e70cfa596a490aa0a30d9 Mon Sep 17 00:00:00 2001
From: Marijn Haverbeke <marijn@haverbeke.berlin>
Date: Tue, 3 Dec 2024 12:57:04 +0100
Subject: [PATCH] Support asserts syntax without predicate

FIX: Allow TypeScript  syntax, where the condition is just a variable.

Issue https://github.com/lezer-parser/javascript/issues/41
---
 src/javascript.grammar | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/javascript.grammar b/src/javascript.grammar
index a1105ad..b4e5423 100644
--- a/src/javascript.grammar
+++ b/src/javascript.grammar
@@ -246,7 +246,12 @@ patternAssign {
 
 TypeAnnotation { ":" type }
 
-TypePredicate { ":" tskw<"asserts">? (VariableName | kw<"this">) !predicate tskw<"is"> type }
+TypePredicate {
+  ":" (
+     tskw<"asserts">? (VariableName | kw<"this">) (tskw<"is"> type)? |
+     (VariableName | kw<"this">) !predicate tskw<"is"> type
+  )
+}
 
 patternAssignTyped {
   pattern Optional? TypeAnnotation? ("=" expressionNoComma)?