JavaScript variable can hold different types of data like integer, float, character, string, function, To check what data currently a variable holds, javascript provide typeof operator.
<!DOCTYPE html>
<html>
<head>
</head>
<body>
<div id="dv_types"></div>
<script>
var name = "yourshala";
var age = 30;
var isValid = false;
var todaysDate = new Date();
var personInfo = {name:'Mickey',Age:30};
var fnc = function(){}
var dv = document.getElementById('dv_types')
dv.innerHTML = typeof name;
dv.innerHTML += '<br/>' + typeof age;
dv.innerHTML += '<br/>' + typeof isValid;
dv.innerHTML += '<br/>' + typeof todaysDate;
dv.innerHTML += '<br/>' + typeof personInfo;
dv.innerHTML += '<br/>' + typeof fnc;
}
</script>
</body>
</html>