PC浏览器中没有plus对象

import { Injectable } from '@angular/core';

declare var window: any;

@Injectable()
export class Plus {

plus: any;
constructor() {
    **this.plus = window.plus == undefined ? null : window.plus;**

}

/**
 * 消息提醒
 * @param msg 消息
 */
toast(msg) {
    **if (this.plus)** {
        this.plus.nativeUI.toast(msg, { duration: "long" });
    } else
    {
        alert(msg)
    }
}

}