// Copyright 2008 the V8 project authors. All rights reserved. // Redistribution and use in source and binary forms, with or without // modification, are permitted provided that the following conditions are // met: // // * Redistributions of source code must retain the above copyright // notice, this list of conditions and the following disclaimer. // * Redistributions in binary form must reproduce the above // copyright notice, this list of conditions and the following // disclaimer in the documentation and/or other materials provided // with the distribution. // * Neither the name of Google Inc. nor the names of its // contributors may be used to endorse or promote products derived // from this software without specific prior written permission. // // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. // const variables should be read-only const c = 42; c = 87; assertEquals(42, c); // const variables are not behaving like other JS variables when it comes // to scoping - in fact they behave more sanely. Inside a 'with' they do // not interfere with the 'with' scopes. (function () { with ({ x: 42 }) { const x = 7; } x = 5; assertEquals(7, x); })(); // const variables may be declared but never initialized, in which case // their value is undefined. (function (sel) { if (sel == 0) with ({ x: 42 }) { const x; } else x = 3; x = 5; assertTrue(typeof x == 'undefined'); })(1); // const variables may be initialized to undefined. (function () { with ({ x: 42 }) { const x = undefined; } x = 5; assertTrue(typeof x == 'undefined'); })(); // const variables may be accessed in inner scopes like any other variable. (function () { function bar() { assertEquals(7, x); } with ({ x: 42 }) { const x = 7; } x = 5 bar(); })(); // const variables may be declared via 'eval' (function () { with ({ x: 42 }) { eval('const x = 7'); } x = 5; assertEquals(7, x); })();