JSFiddle - React, Tailwind, and code Playground

HTML

<button>Button</button>
<div id='myDivId'>
    <div class="progress"></div>
    <div class="content">
        DIV
    </div>
</div>

CSS

#myDivId{background:red; color:white; padding:10px; overflow:hidden; position:relative;}
.content{
    z-index:9;
    position:relative;
}
.progress{
    z-index;1;
    width:0px;
    height:100%;
    position:absolute;
    background:blue;
    left:0px;
    top:0px;
}

JavaScript

$("button").click(function(){ 
      $('.progress').animate({ width: '100%' }, 10000);
});