Nov 9, 2020 · JavaScript has a special operator called typeof which lets you get the type of any value. In this article, we will learn how typeof is used, along with a few gotchas to watch out for.

JavaScript has 7 primitive data types: The typeof operator returns the type of a variable or an expression. In JavaScript, null is a primitive value. However, typeof returns "object". This is a well-known bug in JavaScript and has historical reasons. A complex data type can store multiple values and/or different data types together.

Apr 3, 2025 · The typeof operator returns a string indicating the type of the operand's value.

Dec 22, 2010 · For your example, if you have strict comparison x === y and x = 123, y = "123", it will automatically check typeof x, typeof y and show warning in console: Strict compare of different types: 123 (number) === "123" (string)

Use typeof to solve some basic problem (String, Number, Boolean...) and use Object.prototype.toString to solve something complex (like Array, Date, RegExp). and this is my solution: var cache = {}; return function(obj) { var key; return obj === null ? 'null' // null. : obj === global ? 'global' // window in browser or global in nodejs.

Dec 9, 2022 · In this article, you will learn how to use the typeof operator, instances when you should not use typeof, and the best way to check type in JavaScript for such instances.

Jul 3, 2013 · So what is the best way to detect a variable type? Because a string literal isn't an object of String type. See typeof capitalized. The best way is to use the typeof keyword. The typeof operator maps an operand to one of eight possible values: The instanceof method tests if the provided function's prototype is in the object's prototype chain.

Jan 31, 2022 · In JavaScript, the typeof operator is used to determine the typeof an object or variable. JavaScript, on the other hand, is a dynamically typed (or weakly typed) language. This indicates that a variable can have any type of value. The type of the value assigned to a variable determines the type of the variable.

In JavaScript, properly checking the type of a variable or object is an important skill for writing robust code. The typeof operator provides an easy way to check types, but it has some common pitfalls. In this comprehensive guide, you‘ll learn: Let‘s dive in!

Feb 5, 2025 · Explore JavaScript type checking methods with examples to avoid errors and write more reliable code. Type checking is an important concept in JavaScript. It helps you to understand the kind of data you are working with. JavaScript is a loosely-typed language, which means variables can hold any type of value at any time.