JSFiddle - React, Tailwind, and code Playground

HTML

<div id="legendacep">
    <p> <b>Selecione: </b>

        <br/>
        <input type="radio" name="tipocep" value="1;40.50" class="seltipocep" />PAC <b>R$ 40,50</b> prazo de 28 dia(s)
        <br/>
        <br/>
        <input type="radio" name="tipocep" value="2;129.40" class="seltipocep" />SEDEX <b>R$129,40</b> prazo de 4 dia(s)
        <input type="hidden" name="addfrete" value="1" />
    </p>
</div>

JavaScript

$("#legendacep").on('change', "input[name=tipocep]", function() {                
    alert("sDSDS");
});