JSFiddle - React, Tailwind, and code Playground

HTML

<div id="div1"></div>
<div id="div2"></div>
<select id="divit">
    <option value="div1">div1</option>
    <option value="div2">div2</option>
</select>

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CSS

#div1 { display: block; background-color: red; height:300px; width:300px; }
#div2 { display: none; background-color: blue; height:300px; width:300px; }

JavaScript

function displayVals() {
    switch ($("#divit").val()) {
        case 'div1':
            $("#div1").show();
            $("#div2").hide();
        break;
        case 'div2':
            $("#div1").hide();
            $("#div2").show();
        break;
    }
}
$("#divit").change(displayVals);
displayVals();