Get the data type information with typeof operator
Description
The typeof operator tells the data type of a given variable.
It returns one of the following strings:
| Returned Value | Meanings |
|---|---|
| "undefined" | if the value is undefined |
| "boolean" | if the value is a Boolean |
| "string" | if the value is a string |
| "number" | if the value is a number |
| "object" | if the value is an object or null |
| "function" | if the value is a function |
Example
The typeof operator is called like this:
var message = "hi from java2s.com";
console.log(typeof message); //"string"
console.log(typeof(message)); //"string"
console.log(typeof 95); //"number"
console.log(typeof null);/*from www. j ava2s .c o m*/
var aString;
console.log(typeof aString);
In this example, both a variable (message) and a numeric literal are passed into the typeof operator.
The typeof is an operator and not a
function, no parentheses are required.
Calling typeof null returns a value of "object"
since null is considered to be an empty object reference.
The code above generates the following result.
