repl: fix tab completion for object properties with special char

The old RegExp will pass property names like `"hello world!"`
when filtering the results of tab complete. This change is to
fix it.

Fixes: #21201

Author: starkwang

lib/repl.js

@@ -47,6 +47,10 @@ const {
   makeRequireFunction,
   addBuiltinLibsToObject
 } = require('internal/modules/cjs/helpers');
+const {
+  isIdentifierStart,
+  isIdentifierChar
+} = require('internal/deps/acorn/dist/acorn');
 const internalUtil = require('internal/util');
 const { isTypedArray } = require('internal/util/types');
 const util = require('util');
@@ -900,9 +904,25 @@ const requireRE = /\brequire\s*\(['"](([\w@./-]+\/)?(?:[\w@./-]*))/;
 const simpleExpressionRE =
     /(?:[a-zA-Z_$](?:\w|\$)*\.)*[a-zA-Z_$](?:\w|\$)*\.?$/;
 
-function intFilter(item) {
-  // filters out anything not starting with A-Z, a-z, $ or _
-  return /^[A-Za-z_$]/.test(item);
+function isIdentifier(str) {
+  if (str === '') {
+    return false;
+  }
+  const first = str.codePointAt(0);
+  if (!isIdentifierStart(first)) {
+    return false;
+  }
+  const firstLen = first > 0xffff ? 2 : 1;
+  for (var i = firstLen; i < str.length; i += 1) {
+    const cp = str.codePointAt(i);
+    if (!isIdentifierChar(cp)) {
+      return false;
+    }
+    if (cp > 0xffff) {
+      i += 1;
+    }
+  }
+  return true;
 }
 
 const ARRAY_LENGTH_THRESHOLD = 1e6;
@@ -932,7 +952,7 @@ function filteredOwnPropertyNames(obj) {
 
     return fakeProperties;
   }
-  return Object.getOwnPropertyNames(obj).filter(intFilter);
+  return Object.getOwnPropertyNames(obj).filter(isIdentifier);
 }
 
 function getGlobalLexicalScopeNames(contextId) {

test/parallel/test-repl-tab-complete.js

@@ -369,6 +369,12 @@ putIn.run(['.clear']);
 testMe.complete('.b', common.mustCall((error, data) => {
   assert.deepStrictEqual(data, [['break'], 'b']);
 }));
+putIn.run(['.clear']);
+putIn.run(['var obj = {"hello, world!": "some string", "key": 123}']);
+testMe.complete('obj.', common.mustCall((error, data) => {
+  assert.strictEqual(data[0].includes('obj.hello, world!'), false);
+  assert(data[0].includes('obj.key'));
+}));
 
 // tab completion for large buffer
 const warningRegEx = new RegExp(