JSFiddle - React, Tailwind, and code Playground

HTML

<input type="radio" name="methode" value="" />
<input type="radio" name="methode" value=""/>
<input type="radio" name="methode" value=""/>
<input type="radio" name="methode" value=""/>
<input type="radio" name="methode" value=""/>
<input type="radio" name="methode" value=""/>

JavaScript

function validerRadioGroup(){
	var radioGroup = document.getElementsByName('methode')
	
	var n = radioGroup.length;
 	for (var i=0;i<n;i++){
        
		if (radioGroup[i].checked){
			
            return false;
		}
	}
    
 
	return true;
}
 


if(validerRadioGroup())
{
alert('aucun button coché');
}
else
{
alert('formulaire submit');
}