window.open();
open();

When writing a script, you can use the notation of your choice. However, you should keep in mind that the first specification is much faster. Let's take a look at another object reference:

var url = location.href;

In order for the scripting engine to resolve this reference, it first attempts to find an object named location in the global look-up table. After looking through the entire table and not finding such a named item, the engine has to walk through the table again asking each of the global objects if it supports the location object. When it finally encounters the global window object, the object that exposes the location property, it can then retrieve the href property. A better way to handle this situation, especially on a page containing many globally named items, is to fully scope the reference as follows:

var url = window.location.href;

For more information on these issues, refer to Microsoft's documentation.

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