JSFiddle - React, Tailwind, and code Playground

HTML

<input id='main' type='number'/>
<label><input class='radioButton' type='radio'  name='vol' value='220' checked/>220</label>

<label><input class='radioButton' type='radio' name='vol' value='380'/>380</label>

JavaScript

var elements = document.querySelectorAll('.radioButton');
  
  function getValRadio() {
  
  	for (var i=0; i<elements.length; i++) {
    
    	if (elements[i].checked) {
      
      	return main.value = elements[i].value;
      	
       
      }
      
      return;
    
    }
  
  }
  
  function setValRadio() {
  
  	var value = this.value;
    
    main.value = value;
  
  }
  
  
  for (var i=0; i<elements.length; i++) {
  
  	elements[i].addEventListener('click',setValRadio);
  
  }
  
  
  getValRadio();