从JavasScript ECMAScript 6中的类名创建对象

问题描述

我想使用ES6创建对象工厂，但旧式语法不适用于新版.

I want create object factory using ES6 but old-style syntax doesn't work with new.

我有下一个代码:

export class Column {}
export class Sequence {}
export class Checkbox {}

export class ColumnFactory {
    constructor() {
        this.specColumn = {
            __default: 'Column',
            __sequence: 'Sequence',
            __checkbox: 'Checkbox'
        };
    }

    create(name) {
        let className = this.specColumn[name] ? this.specColumn[name] : this.specColumn['__default'];
        return new window[className](name); // this line throw error
    }
}

let factory = new ColumnFactory();
let column = factory.create('userName');

我该怎么办?

推荐答案

不要将类名放在该对象上.将类本身放在那里，这样您就不必依赖于它们是全局的并且可以通过window访问(在浏览器中).

Don't put class names on that object. Put the classes themselves there, so that you don't have to rely on them being global and accessible (in browsers) through window.

顺便说一句，没有充分的理由将此工厂设置为类，您可能只会实例化一次(单例).只是使其成为对象:

Btw, there's no good reason to make this factory a class, you would probably only instantiate it once (singleton). Just make it an object:

export class Column {}
export class Sequence {}
export class Checkbox {}

export const columnFactory = {
    specColumn: {
        __default: Column,    // <--
        __sequence: Sequence, // <--
        __checkbox: Checkbox  // <--
    },
    create(name, ...args) {
        let cls = this.specColumn[name] || this.specColumn.__default;
        return new cls(...args);
    }
};

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