Scripter Javascript Tutorial

34 typeof comparison

MDN: Operators: typeof

typeof returns true if a variable’s value is a particular data type and uses strings for its returned values.

var str = "foobar";
if ( typeof str == "string" ) {
	Trace(str); // "string"
}
var num = 60;
Trace(typeof num); // "number"

In the above example:

• Line 1: A variable is declared and assigned a string value.

• Line 2: The typeof comparison is used to determine whether or not the value is of type “string”.

• Line 3: If the data type is string, then the script does something with that variable.

• Line 5-6: A variable of the number data type is created and the typeof operator is used to reveal the data type in the console.