Further practice on automatic background changes with JavaScript and CSS

Question

In my previous question, with the help of (Jan) I solved the problem of automatic background change. My previous question: Implementing automatic background changes using JavaScript and CSS but when the background changes, the jump in color is visible and I want the color change to happen seamlessly and slowly. vari=0;functionchangeBackgroundColor(){varbackground=document.getElementById("background&quo

P粉081360775 · Answer

To make the background color change smoothly, you need to add the transition attribute to the background-color attribute. The following code can achieve this effect:

#background{
  width: 100%;
  height: 100%;
  background: #39c787;
  background-image: -webkit-gradient(linear, 15% 0%, 75% 84%, from(#ca83ddc4), to(#7874e3f3), color-stop(70%, #dfa450ab));
  transition: background-color 5s ease;
  -webkit-transition: background-color 5s ease;
  -moz-transition: background-color 5s ease;
  -o-transition: background-color 5s ease;
  -ms-transition: background-color 5s ease;
}

.background-body{
  background: #e0922d !important;
  background-image: -webkit-gradient(linear, 15% 0%, 75% 84%, from(#9283ddc4), to(#22ff12d1), color-stop(70%, #c550dfab)) !important;
  transition: background-color 5s ease;
  -webkit-transition: background-color 5s ease;
  -moz-transition: background-color 5s ease;
  -o-transition: background-color 5s ease;
  -ms-transition: background-color 5s ease;
}

P粉729198207 · Answer

Use an absolutely positioned pseudo-element with a different background, and then make an opacity change transition on top of it.

function changeBackgroundColor() {
  document.body.classList.toggle("alt-background")
  setTimeout(changeBackgroundColor, 4000)
}
changeBackgroundColor()

html, body {
  width: 100%;
  height: 100%;
}

body {
  position: relative;
  margin: 0;
  background-image: linear-gradient(135deg, rgba(131,58,180,1) 0%, rgba(253,29,29,1) 50%, rgba(252,176,69,1) 100%);
}

body::before {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  content: '';
  background-image: linear-gradient(135deg, rgba(2,0,36,1) 0%, rgba(9,9,121,1) 35%, rgba(0,212,255,1) 100%);
  opacity: 0;
  transition: opacity 2s ease-in-out;
}

body.alt-background::before {
  opacity: 1;
}

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