You can use this code snippet for your JWT auth system ( Dependency vuejs and vue-resource )

Cookie.js

import Vue          from 'vue';
import VueResource  from 'vue-resource';

Vue.use(VueResource);

class Cookie
{
    /**
     * Get cookie value by the cookie name.
     *
     * @param string name
     * @return {string|mixed}
     */
    get(name) {
        if( (this._getCookieValue('token_refresh_needed') == '') && (name == 'api_token') ) {
            Vue.http.get('/api/refresh/token?token=' + this._getCookieValue('api_token'))
                .then( (response) => {
                    let token = JSON.parse(response.body).token;

                    this._setTokenRefreshTimer();

                    this.set('api_token', token, this._getCookieValue('token_expires_time'), this._getCookieValue('remember_me'));

                    return this._getCookieValue(name);
                })
        } else {
            return this._getCookieValue(name);
        }
    }

    /**
     * Set cookie value.
     *
     * @param string name
     * @param mixed  value
     * @param int    expires
     * @param bool   rememberMe
     */
    set( name, value, expires = null, rememberMe = false ) {

        let now = new Date();

        this._setTokenRefreshTimer();

        // if remember me is true
        // then set expires time with large number
        if(rememberMe) {
            now.setTime(now.getTime() + 1 * 9999 * 9999 * 1000);

            document.cookie = name + "=" + value + "; expires=" + now.toUTCString() + "; path=/";
            document.cookie = "remember_me=true; expires=" + now.toUTCString() + "; path=/";
        }

        // if expires time is integer
        // then expires data will be set
        else if( _.isInteger(expires) ) {
            now.setTime(now.getTime() + 1 * expires * 1000);

            document.cookie = name + "=" + value + "; expires=" + now.toUTCString() + "; path=/";
            document.cookie = "token_expires_time=" + expires + "; expires=" + now.toUTCString() + "; path=/";
        }

        // by default no expires time will be set
        else {
            document.cookie = name + "=" + value + "; path=/";
        }
    }

    /**
     * Get cookie value.
     *
     * @param string name
     * @return {mixed}
     * @private
     */
    _getCookieValue( name ) {
        let cookieName = name;

        name = cookieName + "=";

        let documentCookie = document.cookie.split(';');

        for(var i = 0; i < documentCookie.length; i++) {
            let cookie = documentCookie[i];

            while (cookie.charAt(0)==' ') {
                cookie = cookie.substring(1);
            }

            if (cookie.indexOf(name) == 0) {
                return cookie.substring(name.length, cookie.length)
            }
        }

        return '';
    }

    /**
     * Set token_refresh_needed cookie to determine
     * the api_token value need to refresh or not
     *
     * @private
     */
    _setTokenRefreshTimer() {
        let now = new Date();

        now.setTime(now.getTime() + 1 * 3000 * 1000);

        document.cookie = "token_refresh_needed=false; expires=" + now.toUTCString() + "; path=/";
    }

    /**
     * Delete cookie.
     *
     * @param string name
     */
    delete( name ) {
        let now = new Date();

        now.setTime(now.getTime() - 1);

        document.cookie = name + "=" + "; expires=" + now.toUTCString() + "; path=/";
    }
}


module.exports = new Cookie;