repl: fix REPL completion under unary expressions

PR-URL: #59744
Fixes: #59735
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

Author: kingsword09

lib/repl.js

@@ -1744,6 +1744,16 @@ function findExpressionCompleteTarget(code) {
     return findExpressionCompleteTarget(lastDeclarationInitCode);
   }
 
+  // If the last statement is an expression statement with a unary operator (delete, typeof, etc.)
+  // we want to extract the argument for completion (e.g. for `delete obj.prop` we want `obj.prop`)
+  if (lastBodyStatement.type === 'ExpressionStatement' &&
+      lastBodyStatement.expression.type === 'UnaryExpression' &&
+      lastBodyStatement.expression.argument) {
+    const argument = lastBodyStatement.expression.argument;
+    const argumentCode = code.slice(argument.start, argument.end);
+    return findExpressionCompleteTarget(argumentCode);
+  }
+
   // If any of the above early returns haven't activated then it means that
   // the potential complete target is the full code (e.g. the code represents
   // a simple partial identifier, a member expression, etc...)

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

@@ -0,0 +1,141 @@
+'use strict';
+
+const common = require('../common');
+const assert = require('assert');
+const repl = require('repl');
+const { describe, it } = require('node:test');
+
+// This test verifies that tab completion works correctly with unary expressions
+// like delete, typeof, void, etc. This is a regression test for the issue where
+// typing "delete globalThis._" and then backspacing and typing "globalThis"
+// would cause "globalThis is not defined" error.
+
+describe('REPL tab completion with unary expressions', () => {
+  it('should handle delete operator correctly', (t, done) => {
+    const r = repl.start({
+      prompt: '',
+      input: process.stdin,
+      output: process.stdout,
+      terminal: false,
+    });
+
+    // Test delete with member expression
+    r.complete(
+      'delete globalThis._',
+      common.mustSucceed((completions) => {
+        assert.strictEqual(completions[1], 'globalThis._');
+
+        // Test delete with identifier
+        r.complete(
+          'delete globalThis',
+          common.mustSucceed((completions) => {
+            assert.strictEqual(completions[1], 'globalThis');
+            r.close();
+            done();
+          })
+        );
+      })
+    );
+  });
+
+  it('should handle typeof operator correctly', (t, done) => {
+    const r = repl.start({
+      prompt: '',
+      input: process.stdin,
+      output: process.stdout,
+      terminal: false,
+    });
+
+    r.complete(
+      'typeof globalThis',
+      common.mustSucceed((completions) => {
+        assert.strictEqual(completions[1], 'globalThis');
+        r.close();
+        done();
+      })
+    );
+  });
+
+  it('should handle void operator correctly', (t, done) => {
+    const r = repl.start({
+      prompt: '',
+      input: process.stdin,
+      output: process.stdout,
+      terminal: false,
+    });
+
+    r.complete(
+      'void globalThis',
+      common.mustSucceed((completions) => {
+        assert.strictEqual(completions[1], 'globalThis');
+        r.close();
+        done();
+      })
+    );
+  });
+
+  it('should handle other unary operators correctly', (t, done) => {
+    const r = repl.start({
+      prompt: '',
+      input: process.stdin,
+      output: process.stdout,
+      terminal: false,
+    });
+
+    const unaryOperators = [
+      '!globalThis',
+      '+globalThis',
+      '-globalThis',
+      '~globalThis',
+    ];
+
+    let testIndex = 0;
+
+    function testNext() {
+      if (testIndex >= unaryOperators.length) {
+        r.close();
+        done();
+        return;
+      }
+
+      const testCase = unaryOperators[testIndex++];
+      r.complete(
+        testCase,
+        common.mustSucceed((completions) => {
+          assert.strictEqual(completions[1], 'globalThis');
+          testNext();
+        })
+      );
+    }
+
+    testNext();
+  });
+
+  it('should still evaluate globalThis correctly after unary expression completion', (t, done) => {
+    const r = repl.start({
+      prompt: '',
+      input: process.stdin,
+      output: process.stdout,
+      terminal: false,
+    });
+
+    // First trigger completion with delete
+    r.complete(
+      'delete globalThis._',
+      common.mustSucceed(() => {
+        // Then evaluate globalThis
+        r.eval(
+          'globalThis',
+          r.context,
+          'test.js',
+          common.mustSucceed((result) => {
+            assert.strictEqual(typeof result, 'object');
+            assert.ok(result !== null);
+            r.close();
+            done();
+          })
+        );
+      })
+    );
+  });
+});