CollapseSidebar is not a function
<p>I am writing a script for a project, it has a function to collapse or open the sidebar on click on hamdurger icon but when I click it gives me error </p>

<blockquote>
  <p>TypeError: this.CollapseSidebar is not a function</p>
</blockquote>

<p>The following is my code:</p>

<pre><code>(function($) {
    'use strict';
    var Prtm = {
        Constants: {
            LEFTMARGIN:'315px',
            COLLAPSELEFTMARGIN: '63px',
        },
        PrtmEle:{
            BODY: $('body'),
            SIDEBAR: $('.prtm-sidebar'),
            SIDENAV: $('.sidebar-nav'),
            MAIN: $('.prtm-main'),
            HEADER: $('.prtm-header'),
            CONTENTWRAP: $('.prtm-content-wrapper'),
            CONTENT: $('.prtm-content'),
            PRTMBLOCK: $('.prtm-block'),
            FOOTER: $('.prtm-footer'),
            HAMBURGER: $('.prtm-bars'),
        },
        Init:function(){
            this.BindEvents();
        },
        BindEvents:function(){
            this.PrtmEle.BODY.on('click',this.PrtmEle.HAMBURGER,function(){
                this.CollapseSidebar();
            });
        },
        CollapseSidebar: function(){
            this.PrtmEle.HAMBURGER.toggleClass("prtm-sidebar-closed is-active");
            this.PrtmEle.BODY.toggleClass("prtm-sidebar-closed is-active");
            this.PrtmEle.SIDEBAR.toggleClass('collapse');
        },
    };
    Prtm.Init();
})(jQuery);
</code></pre>

<p>When I change <code>this.CollapseSidebar</code> to <code>Prtm.CollapseSidebar</code> it works properly. What I am doing wrong here and how it can be resolved?</p>