How can you display a session timeout warning that

问题:

I have implemented a session timeout warning using javascript that simply asks the user if they want to extend their session or logout. The problem is that this is for an intranet portal where power users will often have several browser windows or tabs open at the same time to the application. Currently, they will be prompted that they are about to be logged out from every browser window. How can I make the code smarter to detect that they are actively using another browser session?

回答1:

You'd have to check the session state on the server using Ajax and keep track of all the open sessions/windows the user has. You'd then be able to target only one of the available sessions with the log out warning.

In response to your comment:

Don't use the built-in session mechanism, devise your own using an server-side presistent array or a database log.

No, nothing in the HTTP request tells you how many browsers are open, but you can assign your own sessionID cookie as the user opens each browser window. Make an Ajax call to the server, see if the user has timed-out, and if you're the lowest (or last) entry in the session log then you're the browser that gets the warning.

回答2:

You can't count on all tabs/windows to be part of the same Session, because they could be spawned and contained within separate processes and you don't have much control over that.

But if your code references a Javascript cookie, you can check your pseudo-session state via a postback (synchronous or asynchronous AJAX). But then you're depending on cookies being enabled on the user's browser.

回答3:

Would this work?

Store a Javascript cookie and check that to determine if the session has been extended in another tab?

looks like this does work...

回答4:

Install @ng-idle @ng-idle is available via NPM. Install it by running:

npm install --save @ng-idle/core @ng-idle/keepalive angular2-moment

Set up your application module Open src/app/app.module.ts and import the Ng2IdleModule using

import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import { FormsModule } from '@angular/forms';
import { HttpModule } from '@angular/http';

import { NgIdleKeepaliveModule } from '@ng-idle/keepalive'; // this includes the core NgIdleModule but includes keepalive providers for easy wireup

import { MomentModule } from 'angular2-moment'; // optional, provides moment-style pipes for date formatting

import { AppComponent } from './app.component';

@NgModule({
  declarations: [
    AppComponent
  ],
  imports: [
    BrowserModule,
    FormsModule,
    HttpModule,
    MomentModule,
    NgIdleKeepaliveModule.forRoot()
  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule { }

then in component.ts

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

import {Idle, DEFAULT_INTERRUPTSOURCES} from '@ng-idle/core';
import {Keepalive} from '@ng-idle/keepalive';

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent {

    currentPath: String;

    idleState = 'Not started.';
    timedOut = false;
    lastPing?: Date = null;

    constructor(private idle: Idle, private keepalive: Keepalive, location: Location, router: Router) {

        // sets an idle timeout of 5 seconds, for testing purposes.
        idle.setIdle(5);

        // sets a timeout period of 5 seconds. after 10 seconds of inactivity, the user will be considered timed out.
        idle.setTimeout(5);

        // sets the default interrupts, in this case, things like clicks, scrolls, touches to the document
        idle.setInterrupts(DEFAULT_INTERRUPTSOURCES);

        idle.onIdleEnd.subscribe(() => this.idleState = 'No longer idle.');

        idle.onTimeout.subscribe(() => {
            this.idleState = 'Timed out!';
            this.timedOut = true;
        });

        idle.onIdleStart.subscribe(() => this.idleState = 'You\'ve gone idle!');
        idle.onTimeoutWarning.subscribe((countdown) => this.idleState = 'You will time out in ' + countdown + ' seconds!');

        // Sets the ping interval to 15 seconds
        keepalive.interval(15);

        keepalive.onPing.subscribe(() => this.lastPing = new Date());

        // Lets check the path everytime the route changes, stop or start the idle check as appropriate.
        router.events.subscribe((val) => {

            this.currentPath = location.path();
            if(this.currentPath.search(/authentication\/login/gi) == -1)
                idle.watch();
            else
                idle.stop();

        });
    }

    reset() {
        this.idle.watch();
        this.idleState = 'Started.';
        this.timedOut = false;
    }
}