js之preventExtensions

     const obj = {}
        Reflect.preventExtensions(obj)
        console.log(Reflect.isExtensible(obj));//false
        obj.a = 1
        Object.defineProperty(obj, 'name', {
            value: 'John Doe',
            writable: false,
            configurable: true,
            enumerable: true
        });//报错

        console.log(obj);

• preventExtensions会阻止对象添加属性
• isExtensible：判断对象是否可以添加属性