typeof Operator

Returns a string that identifies the data type of an expression.

typeof[(]expression[)] ;


  • expression
    Required. Any expression.


The typeof operator returns type information as a string. There are eight possible values that typeof returns: "number", "string", "boolean", "object", "function", "date", "undefined" and "unknown".

The parentheses are optional in the typeof syntax.


: All expressions in JScript have a GetType method. This method returns the data type (not a string representing the data type) of the expression. The GetType method provides more information than the typeof operator.


The following example illustrates the use of the typeof operator.

var x : double = Math.PI;
var y : String = "Hello";
var z : int[] = new int[10];

print("The type of x (a double) is " + typeof(x)  );
print("The type of y (a String) is " + typeof(y) );
print("The type of z (an int[]) is " + typeof(z) );

The output of this code is:

The type of x (a double) is number

The type of y (a String) is string

The type of z (an int[]) is object


Version 1

See Also




Operator Precedence

Operator Summary