assert: handle sparse arrays in deepStrictEqual

Detect sparse array ends and add a fail early path for
unequal array length.

PR-URL: https://github.com/nodejs/node/pull/15027
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Yuta Hiroto <hello@about-hiroppy.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>

1 files changed, 8 insertions, 1 deletions

diff --git a/lib/assert.js b/lib/assert.js
index bdc2fcf5a8..70327467ab 100644
--- a/lib/assert.js
+++ b/lib/assert.js
@@ -180,7 +180,14 @@ function strictDeepEqual(actual, expected) {
   if (Object.getPrototypeOf(actual) !== Object.getPrototypeOf(expected)) {
     return false;
   }
-  if (isObjectOrArrayTag(actualTag)) {
+  if (actualTag === '[object Array]') {
+    // Check for sparse arrays and general fast path
+    if (actual.length !== expected.length)
+      return false;
+    // Skip testing the part below and continue in the callee function.
+    return;
+  }
+  if (actualTag === '[object Object]') {
     // Skip testing the part below and continue in the callee function.
     return;
   }