javascript - 将特定参数传递给 React 中具有多个参数的函数

Question

在 React 中，我创建了下面提到的函数:

infoPrint (firstname = '--', middlename = '--', surname = '--')
{
    console.log('Firstname: ', firstname, ', Middle name: ', middlename, ', Surname: ', surname);
}

我在 componentWillMount 中调用这个函数:

componentWillMount() {
    var firstname = 'Naisarg';
    var surname = 'Parmar';
    this.infoPrint(firstname,surname);
}

我得到这个输出:

Firstname: Naisarg, Middle name: Parmar, Surname: --

但我期待这个:

Firstname: Naisarg, Middle name: --, Surname: Parmar

Answer 1

您可以通过传递一个文字对象作为函数的参数来实现:

class User extends Component {
    componentWillMount() {
        var firstname = 'Naisarg';
        var surname = 'Parmar';
        this.infoPrint({ firstname, surname });
    }

    infoPrint({ firstname = '--', middlename = '--', surname = '--' }) {
        console.log('Firstname: ', firstname, ', Middle name: ', middlename, ', Surname: ', surname);
    }
}

这是一种非常常见的模式，对可选参数有很大帮助。

-

如果您不想使用对象，那么您必须以正确的顺序传递所有参数:

class User extends Component {
    componentWillMount() {
        var firstname = 'Naisarg';
        var surname = 'Parmar';
        this.infoPrint(firstname, null, surname);
    }

    infoPrint(firstname = '--', middlename = '--', surname = '--') {
        console.log('Firstname: ', firstname, ', Middle name: ', middlename, ', Surname: ', surname);
    }
}