15 March 2018

3 mins

JavaScript Primitives and Natives

Written by Dean Gilewicz
JS
A primitive is an immutable data value or data type that is not an object and has no properties or methods. In JavaScript, there are 6 primitive data types: string, number, boolean, null, undefined, and symbol. Except for null and undefined, JavaScript automatically boxes (wraps) all primitive values with their native object equivalents in order to access methods using the prototype chain. String for the string primitive:

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 Number for the number primitive.

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 Boolean for the Boolean primitive.

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 Symbol for the Symbol primitive.

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 To get the underlying primitive value out of a boxed (wrapped) value, the valueOf() method can be used:

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 There are many built-in objects (natives) in JavaScript. Some of them include the following…

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 Most of these native objects can be created (instantiated) in a couple of ways. One is using the new keyword followed by the native object name, the other is without the new keyword and using the literal form. Regardless of the approach used, behind the scenes JavaScript acts like you used the new keyword. For example, when creating an array you can use the new keyword followed by Array(..) or the new keyword can be omitted and the literal form used – square [] brackets.

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 Similarly, when using the Object(), Function(), and RegExp() natives, we can omit the new keyword and use the literal form:

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 However, the Date() and Error() natives do not have a literal form:

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 The Symbol() native does not support the new keyword syntax. Every symbol value returned from Symbol() is unique. A symbol value may be used as an identifier for object properties.

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