javascript - Typescript 接口(interface)未捕获类型错误 : Cannot set property

Question

我正在尝试向对象添加类型断言，但在向嵌套对象分配值时遇到 TypeError。

这是片段

interface Person {
    age: number;
    name: string;
    study: {
        schoolName: string
    }
}

let john = {} as Person;

john.age = 25;
john.name = 'John';
john.study.schoolName = 'some school';

console.log(john); // Uncaught TypeError: Cannot set property 'schoolName' of undefined

Typescript Playground 的链接 Link

Answer 1

也许看看 compiled version您的代码片段将为您清除它

var john = {};
john.age = 25;
john.name = 'John';
john.study.schoolName = 'some school';
console.log(john);

如您所见，Typescript 实际上并未初始化研究属性。