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# `$window`
service in module `ng`

## Description

A reference to the browser's `window` object. While `window` is globally available in JavaScript, it causes testability problems, because it is a global variable. In angular we always refer to it through the `$window` service, so it may be overridden, removed or mocked for testing.

Expressions, like the one defined for the `ngClick` directive in the example below, are evaluated with respect to the current scope. Therefore, there is no risk of inadvertently coding in a dependency on a global value in such an expression.

## Example

#### Source

## Demo