Only one CSS animation bar at any point of time

Question

I am using CSS animation to show an indeterminate progress bar. Refer code below. If you'll notice there are 2 moving gradient at any point of time, i.e. when the 1st one reaches 50% of the width, 2nd one starts. I know that I have defined the css that way using webkit-background-size(50% and 100%). However what I am not able to do is make sure that there should be only 1 moving part at any point of time - i.e. once the animation reaches the right end of the div only then it should start it from the left end. Any pointers on this?

Refer https://jsfiddle.net/AnuragSinha/nuokygpe/1/ and corresponding code below.

    @-webkit-keyframes moving-gradient {
    0% { background-position: left bottom; }
    100% { background-position: right bottom; }
    }
    
    .loading-gradient {
    width: 200px;
    height: 30px;
    background: -webkit-linear-gradient(
            left,
            #e9e9e9  50%,
            #eeefef 100%
        ) repeat;
    -webkit-background-size: 50% 100%;
    -webkit-animation-name: moving-gradient;
    -webkit-animation-duration: 1s;
    -webkit-animation-iteration-count: infinite;
    -webkit-animation-timing-function: linear;
    }

<div class="loading-gradient" style="width: 200px; height: 30px"> </div>

Temani Afif · Accepted Answer · 2019-05-06T12:06:41.673

Instead of making the gradient 50% make it 200% and define 2 gradient coloration inside it. Doing so each part of the gradient will cover exactly 100% of the element width then you can animation it from left to right.

.loading-gradient {
  width: 200px;
  height: 30px;
  background: linear-gradient(to left, 
    #e9e9e9 0%  25%, #eeefef 50%,   /* first one take the half*/
    #e9e9e9 50% 75%, #eeefef 100%); /* second one take the other half*/
  background-size: 200% 100%;
  animation: moving-gradient 1s linear infinite;
}

@keyframes moving-gradient {
  0% {
    background-position: right;
  }
 /*100% {
    background-position: left; /* No need to define this since it's the default value*/
  }*/
}

<div class="loading-gradient" style="width: 200px; height: 30px"> </div>

Since the gradient is now having a size bigger than the container, you need to do the opposite animation (from right to left).

More details: Using percentage values with background-position on a linear gradient

Here is another idea where you can consider pseudo element and translate animation:

.loading-gradient {
  width: 200px;
  height: 30px;
  position:relative;
  z-index:0;
  overflow:hidden;
}
.loading-gradient:before {
  content:"";
  position:absolute;
  z-index:-1;
  top:0;
  right:0;
  width:200%;
  bottom:0;
  background: linear-gradient(to left, #e9e9e9 50%, #eeefef 100%);
  background-size: 50% 100%;
  animation: moving-gradient 1s linear infinite;
}

@keyframes moving-gradient {
  100% {
    transform: translate(50%);
  }
}

<div class="loading-gradient" style="width: 200px; height: 30px"> </div>

Only one CSS animation bar at any point of time

1 Answers1