JSFiddle - React, Tailwind, and code Playground

by lollero

HTML

<div class="diff-container">

  <div class="before">
    <img src="https://placeimg.com/640/480/animals/grayscale" alt="">
  </div>
  <div class="after">
    <img src="https://placeimg.com/640/480/animals/grayscale" alt="">  </div>
    
</div>

<div class="diff-container">

  <div class="before">
    <img src="https://placeimg.com/640/480/animals/grayscale" alt="">
  </div>
  <div class="after">
    <img src="https://placeimg.com/640/480/animals/grayscale" alt="">  </div>
    
</div>

CSS

.diff-container {
  position: relative;
  z-index: 0;
  display: inline-block;
}

.diff-container  img{
  display: block;
}

.diff-container .after {
  position: absolute;
  z-index: 1;
  top: 0;
  left: 0;
  overflow: hidden;
  width: 0;
}

.diff-container .after img {
  filter: blur(4px); // Just to differentiate the images from each other
}

JavaScript

$('.diff-container').each(function() {
  $(this).on("mousemove", function( e ) {

    var _this = $(this);
    		x = e.pageX - _this.offset().left,
        y = e.pageY - _this.offset().top;

    _this.find('.after').width( x ); // Vertical
    
  });
});