I have a variable in JavaScript like following :
var testVariable="<input type='radio' name='gender' value='male' checked> Male<br><input type='radio' name='gender' value='female'>Female<br>"
checked
You can parse the string as HTML
var testVariable = "<input type='radio' name='gender' value='male' checked> Male<br><input type='radio' name='gender' value='female'>Female<br>";
var parser = new DOMParser();
var doc = parser.parseFromString(testVariable, "text/html");
var val = doc.querySelector('input[type="radio"][checked]').value;
console.log(val)