Grav-Admin-Plugin/themes/grav/app/utils/keepalive.js

import { config } from 'grav-config';
import { userFeedbackError } from './response';
import { showSessionExpiredModal } from './session-expired';

const MAX_SAFE_DELAY = 2147483647;

class KeepAlive {
    constructor() {
        this.active = false;
    }

    start() {
        let timeout = config.admin_timeout / 1.5 * 1000;
        this.timer = setInterval(() => this.fetch(), Math.min(timeout, MAX_SAFE_DELAY));
        this.active = true;
    }

    stop() {
        clearInterval(this.timer);
        this.active = false;
    }

    checkOnce() {
        let data = new FormData();
        data.append('admin-nonce', config.admin_nonce);

        return fetch(`${config.base_url_relative}/task${config.param_sep}keepAlive`, {
            credentials: 'same-origin',
            headers: {
                'Accept': 'application/json'
            },
            method: 'post',
            body: data
        })
            .then((response) => {
                if (response && (response.status === 401 || response.status === 403)) {
                    return false;
                }
                return true;
            })
            .catch(() => false);
    }

    fetch() {
        return this.checkOnce().then((ok) => {
            if (!ok) { showSessionExpiredModal(); }
        }).catch(userFeedbackError);
    }
}

export default new KeepAlive();