Complex Data Type in JavaScript includes the typeof operator. The typeof operator is a unary operator that is placed before its single operand, which can be of any type. Its value is a string indicating the data type of the operand.
The typeof operator evaluates to "number", "string", or "boolean" if its operand is a number, string, or boolean value and returns true or false based on the evaluation.
Example
You can try to run the following code to learn how to work with typeof operator in JavaScript −
<html>
<body>
<script>
<!--
var a = 10;
var b = "String";
var linebreak = "<br />";
result = (typeof b == "string" ? "B is String" : "B is Numeric");
document.write("Result => ");
document.write(result);
document.write(linebreak);
result = (typeof a == "string" ? "A is String" : "A is Numeric");
document.write("Result => ");
document.write(result);
document.write(linebreak);
//-->
</script>
</body>
</html>