无法在 javascript 构造函数中访问自己的属性

Question

我有一个基类和另一个扩展它的类，我如何访问构造函数中的字段？

class BaseModel {
    constructor() {
        console.log('no fields :(')
        console.log(this.fields)
        this.fields.map((field) => {
            field.label = field.label || field.name;
        })
    }
}

class UserModel extends BaseModel {
    fields = [
        { name: 'id' },
        { name: 'name' },
        { name: 'email' },
    ];
    constructor(name, email) {
        super();
        this.name = name;
        this.email = email;
    }
}

const user = new UserModel('bob', '[email protected]');
console.log(user);

我翻了大约 2 页，但没有找到关于如何设置的令人满意的答案。我发现最好的方法是在构造函数中设置超时，这似乎是错误的。

Answer 1

如果您想在父构造函数同步中访问

fields

，您应该将字段传递给它：

class BaseModel {
    constructor(fields) {
        this.fields = fields;
        console.log(this.fields)
        this.fields.map((field) => {
            field.label = field.label || field.name;
        })
    }
}

class UserModel extends BaseModel { 
    constructor(name, email) {
        super([
            { name: 'id' },
            { name: 'name' },
            { name: 'email' },
        ]);
        this.name = name;
        this.email = email;
    }
}

const user = new UserModel('bob', '[email protected]');
console.log(user);