app.js

const sections = document.querySelectorAll('.section');
const sectBtns = document.querySelectorAll('.controls');
const sectBtn = document.querySelectorAll('.control');
const allSections = document.querySelector('.main-content');

function PageTransitions(){
    // Button click active class
    for(let i =0; i < sectBtn.length; i++){
        sectBtn[i].addEventListener('click', function(){
            let currentBtn = document.querySelectorAll('.active-btn');
            currentBtn[0].className = currentBtn[0].className.replace('active-btn', '');
            this.className += ' active-btn'
        })
    }
    // Sections active class
    allSections.addEventListener('click',(e) => {
        const id = e.target.dataset.id;
        if (id){
            //remov selected from the other btns
            sectBtns.forEach((btn) =>{
                btn.classList.remove('active')
            })
            e.target.classList.add('active')

            //hide other sections
            sections.forEach((section)=>{
                section.classList.remove('active')
            })

            const element = document.getElementById(id);
            element.classList.add('active')
        }
    })

    //Toggle theme
    const themeBtn = document.querySelector('.theme-btn');
    themeBtn.addEventListener('click',() =>{
        let element = document.body;
        element.classList.toggle('dark-mode');
    })
}

PageTransitions ()

var TxtType = function(el, toRotate, period) {
    this.toRotate = toRotate;
    this.el = el;
    this.loopNum = 0;
    this.period = parseInt(period, 10) || 2000;
    this.txt = '';
    this.tick();
    this.isDeleting = false;
};

TxtType.prototype.tick = function() {
    var i = this.loopNum % this.toRotate.length;
    var fullTxt = this.toRotate[i];

    if (this.isDeleting) {
    this.txt = fullTxt.substring(0, this.txt.length - 1);
    } else {
    this.txt = fullTxt.substring(0, this.txt.length + 1);
    }

    this.el.innerHTML = '<span class="wrap">'+this.txt+'</span>';

    var that = this;
    var delta = 200 - Math.random() * 100;

    if (this.isDeleting) { delta /= 2; }

    if (!this.isDeleting && this.txt === fullTxt) {
    delta = this.period;
    this.isDeleting = true;
    } else if (this.isDeleting && this.txt === '') {
    this.isDeleting = false;
    this.loopNum++;
    delta = 500;
    }

    setTimeout(function() {
    that.tick();
    }, delta);
};

window.onload = function() {
    var elements = document.getElementsByClassName('typewrite');
    for (var i=0; i<elements.length; i++) {
        var toRotate = elements[i].getAttribute('data-type');
        var period = elements[i].getAttribute('data-period');
        if (toRotate) {
          new TxtType(elements[i], JSON.parse(toRotate), period);
        }
    }
    // INJECT CSS
    var css = document.createElement("style");
    css.type = "text/css";
    css.innerHTML = ".typewrite > .wrap { border-right: 0.06em solid #646464}";
    document.body.appendChild(css);
};