JSFiddle - React, Tailwind, and code Playground

HTML

<body>
<a id="changediv">changediv</a>
<br>
<div id="div1">Div1</div>
<div id="div2">Div2</div>
</body>

CSS

body{
    width:400px;
}
#div1{
    width:400px;
    height:200px;
    background-color: #06c;
    float: left;
    overflow: hidden;
}
#div2{
    width:0px;
    height:200px;
    background-color: #ff6600;
    float: right;
    overflow: hidden;
}

JavaScript

$('#changediv').click(
function() {
    $('#div1').animate({"width": 0}, "slow");
    $('#div2').animate({"width": 400}, "slow");
});