JSFiddle - React, Tailwind, and code Playground
HTML
<div id='LookupSection'>
Input Type
<input type="radio" name="StatusOnHeader" value="Edit">Edit existing
<input type="radio" name="StatusOnHeader" value="Add" checked>Add new
</div>
<input type="submit" class='buttons' name="send_button" value="Save" onclick='commitData()'>   
JavaScript
function commitData()
{
switch (true) {
case document.getElementsByName('StatusOnHeader')[0]:
alert('Edit');
break;
case document.getElementsByName('StatusOnHeader')[1]:
alert('Add');
break;
default:
alert('XXX');
break;
}
if (document.getElementsByName('StatusOnHeader')[0]) {
alert("TRUE");
} else {
alert("FALSE");
}
if (document.getElementsByName('StatusOnHeader')[0] == true) {
alert("TRUE");
} else {
alert("FALSE");
}
if (document.getElementsByName('StatusOnHeader')[0] == 1) {
alert("TRUE");
} else {
alert("FALSE");
}
if (document.getElementsByName('StatusOnHeader')[0] == '1') {
alert("TRUE");
} else {
alert("FALSE");
}
switch (document.getElementsByName('StatusOnHeader')[0]) {
case true:
alert('Edit');
break;
case false:
alert('Add');
break;
default:
alert('XXX');
break;
}
}