Micro-optimize memfs readdir. NFC

Author: sbc100

src/library_memfs.js

@@ -198,10 +198,8 @@ addToLibrary({
             new_node = FS.lookupNode(new_dir, new_name);
           } catch (e) {
           }
-          if (new_node) {
-            for (var i in new_node.contents) {
-              throw new FS.ErrnoError({{{ cDefs.ENOTEMPTY }}});
-            }
+          if (new_node && Object.keys(new_node.contents).length) {
+            throw new FS.ErrnoError({{{ cDefs.ENOTEMPTY }}});
           }
         }
         // do the internal rewiring
@@ -216,18 +214,14 @@ addToLibrary({
       },
       rmdir(parent, name) {
         var node = FS.lookupNode(parent, name);
-        for (var i in node.contents) {
+        if (Object.keys(node.contents).length) {
           throw new FS.ErrnoError({{{ cDefs.ENOTEMPTY }}});
         }
         delete parent.contents[name];
         parent.ctime = parent.mtime = Date.now();
       },
       readdir(node) {
-        var entries = ['.', '..'];
-        for (var key of Object.keys(node.contents)) {
-          entries.push(key);
-        }
-        return entries;
+        return ['.', '..', ...Object.keys(node.contents)];
       },
       symlink(parent, newname, oldpath) {
         var node = MEMFS.createNode(parent, newname, 0o777 | {{{ cDefs.S_IFLNK }}}, 0);

test/other/codesize/test_codesize_cxx_ctors1.gzsize

@@ -1 +1 @@
-8479
+8472

test/other/codesize/test_codesize_cxx_ctors1.jssize

@@ -1 +1 @@
-20708
+20701

test/other/codesize/test_codesize_cxx_ctors2.gzsize

@@ -1 +1 @@
-8462
+8456

test/other/codesize/test_codesize_cxx_ctors2.jssize

@@ -1 +1 @@
-20676
+20669

test/other/codesize/test_codesize_cxx_except.gzsize

@@ -1 +1 @@
-9504
+9491

test/other/codesize/test_codesize_cxx_except.jssize

@@ -1 +1 @@
-24551
+24544

test/other/codesize/test_codesize_cxx_except_wasm.gzsize

@@ -1 +1 @@
-8447
+8439

test/other/codesize/test_codesize_cxx_except_wasm.jssize

@@ -1 +1 @@
-20602
+20595

test/other/codesize/test_codesize_cxx_except_wasm_exnref.gzsize

@@ -1 +1 @@
-8447
+8439