JSFiddle - React, Tailwind, and code Playground

HTML

<form name="teenageMutant">
<input value="aa" type="radio" name="ninjaTurtles"/>
<input value="bb" type="radio" name="ninjaTurtles"/>
<input value="cc" type="radio" name="ninjaTurtles" checked/>
</form>

JavaScript

document.teenageMutant.ninjaTurtles[0].checked=true;
alert(document.teenageMutant.ninjaTurtles[0].checked);