• HTML
• CSS
• JS

HTML

<div class="toggle"></div>

CSS

*{
    margin:0;
    padding:0;
    box-sizing:border-box;
}
body{
    height:100vh;
    display:flex;
    align-items:center;
    justify-content:center;
    background:#7d2ae8;
}
.toggle{
    position:relative;
    height:12px;
    width:125px;
    cursor:pointer;
    border-radius:25px;
    background-color:#fff;
    box-shadow:0 5px 10px rgba(0,0,0,0.1);
}
.toggle::before{
    content:"";
    position:absolute;
    left:0;
    top:50%;
    transform:translateY(-50%);
    height:50px;
    width:50px;
    border-radius:50%;
    background-color:#7d2ae8;
    border:10px solid #fff;
    box-shadow:0 5px 10px rgba(0,0,0,0.1);
    transition:all 0.5s cubic-bezier(0.68,-0.55,0.265,1.55);
}
.toggle.active::before{
    left:calc(100% - 70px);
    background-color:#fff;
    border-color:#7d2ae8;
}

JS

const toggleBtn = document.querySelector(".toggle");

toggleBtn.addEventListener("click",() => toggleBtn.classList.toggle("active"));

/* All the credits: https://www.youtube.com/watch?v=BqjSWo2Zy7s */