Javascript Typeof Function

We will get quotfunctionquot as the output in this example when we pass the operands to typeof in JavaScript. The typeof operator will return this result when we give a user-defined function, a predefined function, or a class as an operand. console.logtypeof function console.logtypeof Math.tanconsole.logtypeof class C Output

The typeof operator returns a string indicating the type of the operand's value.

Learn how to use the typeof operator to get a string representing the type of a value, variable, or expression. See examples of different types, such as string, number, object, and function, and how to use parentheses with expressions.

So always rely on these specialized functions over plain typeof when dealing with edge cases. But there is an even better generic type checking solution A Reusable typeOf Function in JavaScript. We can leverage Object.prototype.toString to create a reusable typeOf function that works consistently across all values. Here's how it works

Easiest way to check the value type in JavaScript is by using the typeof operator. We will explore how typeof works, its use cases and limitations. 9 console. log typeof function Output quotfunctionquot Limitations of typeof. typeof null returns object This is a well-known quirk haunting the language from its early days. There is a

host objects don't have prototypes in IE6 and yet can be functions. Hence typeof window.alertquotfunctionquot window.alert instanceof Function returns false. You can still test for such functions in IE6 by first checking if it's a host object and then by testing if its toString method is either quotundefinedquot or quotunknownquot.

The typeof operator returns the data type of a JavaScript variable. Primitive Data Types In JavaScript, a primitive value is a single value with no properties or methods.

typeof null returns quotobjectquot a known quirk. Functions return quotfunctionquot instead of quotobjectquot. Useful for checking types in dynamic or untyped environments. Syntax typeof operand. operand The value or variable to check. Real-World Examples Example 1 Validating User Input JavaScript

Learn how to use the typeof operator to get the type of any value in JavaScript, and the common gotchas and limitations of this operator. Also, explore better ways to do type checking with instanceof, Object.prototype.toString, and other methods.

Uses of typeof Operator. The typeof operator can be used to check the type of a variable at a particular point. For example, let count 4 console.logtypeof count count true console.logtypeof count You can perform different actions for different types of data. For example,