控制台输入1：
let observer21 = new Observer({
name: 'youngwind',
age: 25
});
observer21.data.name = {
lastName: 'liang',
firstName: 'shaofeng'
};
observer21.data.name.lastName;
observer21.data.name.firstName = 'lalala';
控制台输入2：
let observer22 = new Observer({
name: 'youngwind',
age: 25
});
observer22.$watch('age', function(age) {
console.log(`我的年纪变了，现在已经是：${age}岁了`)
});
observer22.data.age = 100;