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Further practice on automatic background changes with JavaScript and CSS

<p>In my previous question, with the help of (Jan) I solved the problem of automatic background change. </p> <p>My previous question: Automatic background changes using JavaScript and CSS</p> <p>But when the background changes, the jump in color is visible, and I want the color change to be seamless and slow. </p> <p><br /></p> <pre class="brush:js;toolbar:false;">var i = 0; function changeBackgroundColor() { var background = document.getElementById("background"); if (i % 2 === 0) { background.classList.remove("background-body"); } else { background.classList.add("background-body"); } i = i 1; } setInterval(changeBackgroundColor, 3 * 1000);</pre> <pre class="brush:css;toolbar:false;">html,body{ width: 100%; overflow-x: hidden !important; height: 100%; overflow-y: hidden !important; } #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: all 5s ease; -webkit-transition: all 5s ease; -moz-transition: all 5s ease; -o-transition: all 5s ease; -ms-transition: all 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: all 5s ease; -webkit-transition: all 5s ease; -moz-transition: all 5s ease; -o-transition: all 5s ease; -ms-transition: all 5s ease; }</pre> <pre class="brush:html;toolbar:false;"><script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"> ;</script> <body id="background"></body></pre> <p><br /></p>
P粉875565683P粉875565683472 days ago553

reply all(2)I'll reply

  • P粉081360775

    P粉0813607752023-08-16 15:17:43

    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;
}

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  • P粉729198207

    P粉7291982072023-08-16 09:38:10

    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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