How to get value of selected radio button?

Question

I want to get the selected value from a group of radio buttons.

Here\'s my HTML:

Answer 1

https://codepen.io/anon/pen/YQxbZJ

The HTML

 Fixed Rate
 Variable Rate
 Multi Rate


 Check Radio 

The JS

var x ,y;
var x = document.getElementById("check");
function boom()
{
if (document.getElementById("x1").checked)
  y = document.getElementById("x1").value;

else if(document.getElementById("x2").checked)
  y = document.getElementById("x2").value;

else if (document.getElementById("x3").checked)
  y = document.getElementById("x3").value;
else
  y = "kuch nhi;"
x.innerHTML = y;
}

var z = document.getElementById('rdio');
z.addEventListener("click", boom);`