JAVASCRIPT

js check if radio button is checked

if(document.getElementById('gender_Male').checked) {
  //Male radio button is checked
}else if(document.getElementById('gender_Female').checked) {
  //Female radio button is checked
}

javascript radio button value if checked

//alert(document.querySelector('input[name = "comp"]:checked').value);

$test=document.querySelector('input[name = "comp"]:checked').value;

if($test="silver") {
        amount=50;
    }else if($test="gold") {
      amount=90;
    }else{
      amount=30;
    }

javascript is radio button checked

//get radio Buttons (other ways to do this too)
let radioButtons = document.querySelectorAll("input[name=myRadioName]");

//annoyingly the "change" event only fires when a radio button is clicked
//so it does not fire when another one is clicked and it gets unchecked
//so you have to put change listener  on all radio buttons
//and then detect which one is actually selected
for (let i = 0; i < radioButtons.length; i++) {
  	radioButtons[i].addEventListener('change', function() {
  		if (radioButtons[i].checked == 1){
        	alert("checked") ;
    	} else {
    		alert("not checked")
    	}
    });
}

//html look like this:
<form name="myFormName">
  <input type="radio" name="myRadioName"  value="1" />
  <input type="radio" name="myRadioName"  value="2" />
  <input type="radio" name="myRadioName"  value="3" />
</form>