The visible() method, called without any parameters, will return true if the Timeline widget is visible and false otherwise.
The visible(bool) method is used to update a Timeline's visible state. Passing true will show and false will hide it.

<div id="timeline" />

<script type="text/javascript">
    $(function () {
              dataSource: {
                    data: [
                            title: "David F.",
                            text: "Hey! Sure, I will message ...",
                            icon: "myIcon.ico",
                            iconCls: "fa fa-facebook",
                            collapsed: true
                            title: "Followed",
                            text: "By J.R. Simpson",
                            icon: "myIconNext.ico",
                            iconCls: "fa fa-twitter"

    // hide Timeline widget