JavaScript 中的 freeze 和 seal 和有什么不一样？

freeze和seal都用于在 JavaScript 中创建不可扩展的对象，但它们之间有很多不同之处。 Object.seal()允许更改对象的现有属性，而Object.freeze()不允许这样做。 Object.freeze()使对象对所有事物都免疫，即使无法进行微小的更改。 Object.seal()防止删除现有属性，但不能防止它们受到外部更改。句法：

Object.freeze(objectname);

示例 1：描述Object.seal()的实现。

javascript

    // creates an object
    var obj = {
        // assigns 10 to value
        value: 10
    };
    // creates a non-extensible object
    Object.seal(obj);
    // the value gets updated to 20
    obj.value = 20;
    console.log(obj.value);

输出：

20

示例 1描述了如何使用Object.seal()创建一个不可扩展的对象，但这并不能阻止对象的值被更改，并且可以看到该值被更新为 20。语法：

Object.seal(objectname);

示例 2：描述Object.freeze()的实现。

javascript

    // creates an object
    var obj = {
        // assigns 10 to value
        value: 10
    };
    // creates a non-extensible object
    Object.freeze(obj);
    // updates the value
    obj.value = 20;
    // but cannot change the existing value
    console.log(obj.value);

输出：

10

示例 2描述了如何使用Object.freeze()创建不可扩展的对象，但阻止更改对象的现有值并给出 10 作为输出。

让我们以表格形式查看差异 - ：

	freeze	seal
1.	freeze() is a javascript object which is used to prevent the object from adding new properties	seal() is a Javascript method which is used to make properties of an object non-configurable.
2.	It is also used so that the current existing properties should not be modified	It is also used so that the new properties does not gets added
3.	Its syntax is -: Object.freeze(object)	Its syntax is -: Object.seal(object)
4.	It takes a parameter as an object	It takes parameters as an object
5.	Its return type is of the object type.	Its return type is of the sealed object type.
6.	Its supported browsers are -: Chrome , Internet Explorer, Safari, Microsoft Edge, Opera Firefox	Its supported browsers are -: Chrome , Internet Explorer, Safari, Microsoft Edge, Opera, Firefox