javascript - ES5 中 Object.freeze 的效果可以逆转吗？

Question

一旦我这样做:

var x = { };
Object.freeze( x );

有什么办法可以修改x吗？ 谢谢。

Answer 1

Nothing can be added to or removed from the properties set of a frozen object. Any attempt to do so will fail, either silently or by throwing a TypeError exception (most commonly, but not exclusively, when in strict mode).

https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Object/freeze

你可以这样想:

if( typeof ChuckNorris === 'undefined' ) {
    ChuckNorris = Object.create( [Infinity], {
        canCountTo: {
            value: Infinity * 2,
            writable: true,
            configurable: true
        }
    });

    Object.freeze( ChuckNorris ); // nothing can harm Chuck anymore !
}

console.log( ChuckNorris.canCountTo );  // Infinity
delete ChuckNorris.canCountTo;
console.log( ChuckNorris.canCountTo );  // Infinity

所以基本上，freeze 会在创建后将对象的 writable 和 configurable 标志设置为 false。