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This article will explain in detail what is the use of instanceof in js. The editor thinks it is very practical, so I share it with you for reference. I hope you can get something after reading this article.

Instanceof

Instanceof can correctly determine the type of object, because the internal mechanism is to determine whether the type prototype can be found in the prototype chain of the object.

Console.log (2 instanceof Number); / / falseconsole.log (true instanceof Boolean); / / falseconsole.log ('str' instanceof String); / / falseconsole.log ([] instanceof Array); / / trueconsole.log (function () {} instanceof Function); / / trueconsole.log ({} instanceof Object) / / true / / console.log (undefined instanceof Undefined); / / console.log (null instanceof Null)

It can be seen that the literal value determines the data type directly, and instanceof can accurately judge the reference data type (Array,Function,Object), while the basic data type can not be accurately judged by instanceof.

Let's take a look at the explanation of instanceof in MDN: the instanceof operator is used to test whether an object has a prototype property of a constructor in its prototype chain. It means to determine whether an object is an instance of a data type, such as Array, and focus on determining whether an object is an instance of a data type. Here the literal value, 2, true, 'str' is not an instance, so the judgment value is false.

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