javascript - 错误 : *. default is not a constructor

Question

在测试从 typescript 文件转译的一些 javascript 代码时，出现以下错误。

这里是错误:

Error: _mapAction2.default is not a constructor

这是导致错误的代码行:

var mapAction = new MapAction(MapActionType.POLYGONDRAGGED, []);

这是原始的 typescript 文件 ma​​p-action.ts:

import { IMapAction} from './imap-action';
import { MapActionType } from './map-action-type.enum';
import {LatLngLiteral} from 'angular2-google-maps/core';

export class MapAction implements IMapAction{
    type: MapActionType;
    paths: Array<LatLngLiteral>;

    constructor(mapActionType: MapActionType, paths: Array<LatLngLiteral>){
        this.type = mapActionType;
        this.paths = paths;
    }

    public getType(): MapActionType{
        return this.type;
    }

    public getPaths(): Array<LatLngLiteral>
    {
        return this.paths;
    }

}

这是转译后的 .js 文件 ma​​p-action.js:

"use strict";
class MapAction {
    constructor(mapActionType, paths) {
        this.type = mapActionType;
        this.paths = paths;
    }
    getType() {
        return this.type;
    }
    getPaths() {
        return this.paths;
    }
}
exports.MapAction = MapAction;
//# sourceMappingURL=map-action.js.map

Answer 1

您需要导出一个默认值，如下所示:

export default class MapAction implements IMapAction {...

并将其导入为:

import MapAction from './map_action_file';

或者，如果你想从模块中导出多个东西，你可以这样做:

export class MapAction ...
export class MapSomethng ...

并按如下方式导入:

import { MapAction, MapSomething } from './map_action_file';