Changing background color on scroll with javascript

Question

https://codepen.io/tobiasthaden/pen/OVWKjm

$(window).scroll(function() {
  $('section').each(function(i) {
    if ($(this).position().top <= $(window).scrollTop()) {
      $('body').css('background-color', $(this).attr('data-color'));
    }
  });
});

Looking to replicate this effect using regular old javascript. I don’t want to use jQuery!

Any tips?

Answer 1

I would have done it like this.

const sections = document.querySelectorAll('section')

document.addEventListener('scroll', () => {
  sections.forEach(section => {
    if(section.getBoundingClientRect().top <= document.body.scrollTop) {
      document.body.style.background = section.dataset.color
    }    
  })
})

body {
  transition: background-color .2s ease;
}

section {
  height: 100vh;
}

<section data-color="white"></section>
<section data-color="green"></section>
<section data-color="purple"></section>
<section data-color="yellow"></section>
<section data-color="blue"></section>
<section data-color="white"></section>