(function() {
    'use strict';
    var btns = document.querySelectorAll('[data-open]')
    let prev = null

    for (var i = 0; i < btns.length; i++) {
        ;btns[i].addEventListener('click', function (e) {
            
            const iam = Array.from(document.body.children).filter(el => !el.hidden)[0];
            console.log({iam, prev})


            iam.hidden = true;
            if (this.dataset.open === 'prev') {
                prev.hidden = false;
            } else {
                document.getElementById(this.dataset.open).hidden = false
            }
            prev = iam
            console.log({iam, prev})
        })
    }

}());