Introduction to typeof JavaScript

JavaScript is a popular programming language used to create interactive web pages and dynamic web applications. One of the essential operators in JavaScript is typeof, which allows developers to determine the data type of a variable or expression.

Syntax

The syntax for typeof is as follows:

typeof operand

where operand can be any variable or expression in JavaScript.

Examples

The following are examples of using typeof in JavaScript:

typeof 42; // "number"
typeof "Hello, World!"; // "string"
typeof true; // "boolean"
typeof undefined; // "undefined"
typeof null; // "object"
typeof []; // "object"
typeof {}; // "object"
typeof function(){}; // "function"

When used with undefined, null, arrays ([]), and objects ({}), typeof returns "undefined", "object", and "object", respectively. This is because arrays and objects are considered special types of objects in JavaScript.

Conclusion

typeof is a powerful operator in JavaScript that allows developers to determine the data type of any variable or expression. By using typeof, developers can write more robust and efficient code, as they can check for the correct data type before performing any operations on it.