CODEWITHSUNDEEP
javascriptjquery
Felipe Alarcon
Felipe Alarcon

Reputation: 956

How to change a div background colour every X seconds in jQuery without effect?

I have a list with some rgb colours like this:

var ls = ['rgb(255,0,0)','rgb(0,255,0)', 'rgb(0,0,255)'];

And I would like to update a div background colour every 2 seconds using the colours from the list. To achieve it, I have written the following code:

(function($){
  var $box    = $('#box');
  var temp;

  var ls = ['rgb(255,0,0)','rgb(0,255,0)', 'rgb(0,0,255)'];

  $.each(ls, function(i, x){
    temp = setInterval(change(x), 2000);
  });

  function change(color) {
    $box.css('background-color', color);
  }

})(jQuery);

My goal is to display every colour in the list for 2 seconds before moving on to the next colour but this code waits 2 seconds and executes the loop so I can only see the last colour which is blue (rgb(0,0,255)).

My HTML looks like this:

<html>
<head>
  <title>bin</title>
  <style>
    #box{
      width: 200px;
      height: 200px;
      background-color: rgb(0,0,0);
    }
  </style>
</head>

<body>

   <div id="box"></div>
   <script src="https://code.jquery.com/jquery-1.11.3.js"></script>
   <script src="main.js"></script>
</body>
</html>

Thanks everyone.

Upvotes: 0

Views: 1724

Answers (3)

Felipe Alarcon
Felipe Alarcon

Reputation: 956

I have found a nicer way using keyframesto achieve this color transition using plain css although this technique is not supported by IE9 and lower but I thought it'd be worth adding it here in case someone is reading.

<!DOCTYPE html>
<html>
<head>
<style> 
div {
    width: 100px;
    height: 100px;
    background-color: red;
    -webkit-animation-name: example; /* Chrome, Safari, Opera */
    -webkit-animation-duration: 4s; /* Chrome, Safari, Opera */
    animation-name: example;
    animation-duration: 4s;
}

/* Chrome, Safari, Opera */
@-webkit-keyframes example {
    0%   {background-color: red;}
    25%  {background-color: yellow;}
    50%  {background-color: blue;}
    100% {background-color: green;}
}

/* Standard syntax */
@keyframes example {
    0%   {background-color: red;}
    25%  {background-color: yellow;}
    50%  {background-color: blue;}
    100% {background-color: green;}
}
</style>
</head>
<body>

<p><b>Note:</b> This example does not work in Internet Explorer 9 and earlier versions.</p>

<div></div>

</body>
</html>

Here is a DEMO

Upvotes: 1

Tomalak
Tomalak

Reputation: 338148

It all comes down to saving iteration state somewhere. For example like this:

function Cycle(array) {
    var i = 0;
    this.next = function () {
       i %= array.length;
       return array[i++];
    }
}

and 

var colors = new Cycle(['rgb(255,0,0)','rgb(0,255,0)', 'rgb(0,0,255)']);

$('#box').css('background-color', colors.next());

setInterval(function () {
    $('#box').css('background-color', colors.next())
}, 2000);

Upvotes: 3

jcubic
jcubic

Reputation: 66478

You're executing change before setInterval, instead you should add anonymous function and call your change function inside.

  $.each(ls, function(i, x){
    temp = setInterval(function() { change(x); }, 2000);
  });

Upvotes: 1

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