JavaScript: The Definitive Guide

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Variables and Data Types

3.8 Null

The JavaScript keyword null is a special value that indicates "no value." Technically speaking, null is a value of object type, so when a variable holds the value null, you know that it does not contain a valid object or array. For that matter, you also know that it does not contain a valid number, string, Boolean or function.

C and C++ programmers should note that null in JavaScript is not the same as 0 as it is in those languages. In certain circumstances, null will be converted to a 0, but the two are not equivalent.

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