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# undefined

The global **`undefined`** property represents the primitive
value `undefined`. It is one of JavaScript's "primitive types".

## Value

The primitive value `undefined`.

## Description

`undefined` is a property of the _global object_. That is, it is a variable in global scope.

`undefined` is a non-configurable, non-writable property.

A variable that has not been assigned a value is of type `undefined`. A
method or statement also returns `undefined` if the variable that is being
evaluated does not have an assigned value. A function returns `undefined` if
a value was not explicitly returned.
