JSTests/test262/test/language/expressions/delete/11.4.1-5-2.js

// Copyright (c) 2012 Ecma International.  All rights reserved.
// This code is governed by the BSD license found in the LICENSE file.

/*---
es5id: 11.4.1-5-2
description: >
    delete operator returns false when deleting a direct reference to
    a function argument
flags: [noStrict]
---*/

  function foo(a,b) {
  
    // Now, deleting 'a' directly should fail
    // because 'a' is direct reference to a function argument;
    var d = delete a;
    return (d === false && a === 1);
  }

assert(foo(1,2), 'foo(1,2) !== true');