阻止对象扩展后:

var fruit = {
    name : ‘苹果‘,
    desc : ‘红富士‘
};
//
console.log(‘isExtensible‘,Object.isExtensible(fruit)); // true
Object.preventExtensions(fruit);
console.log(‘isExtensible‘,Object.isExtensible(fruit)); // false
//
fruit.address = ‘烟台‘;
console.log(‘添加address属性‘,fruit);
//
fruit.desc = ‘金帅‘;
console.log(‘修改属性‘,fruit);
// 
delete(fruit.desc);
console.log(‘删除属性‘,fruit);
//
Object.defineProperty(fruit,‘desc‘,{
    enumerable : false
});
console.log(‘修改属性描述符为不可枚举‘,Object.keys(fruit));
Object.defineProperty(fruit,‘desc‘,{
    enumerable : true
});
console.log(‘修改属性描述符为可枚举‘,Object.keys(fruit));