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This article mainly explains "how to view the data types of JavaScript variables", the content of the explanation is simple and clear, easy to learn and understand, the following please follow the editor's ideas slowly in depth, together to study and learn "how to view the data types of JavaScript variables" bar!

Typeof operator

You can use the typeof operator to view the data type of the JavaScript variable.

Example

Typeof "John" / / returns string

Typeof 3.14 / / returns number

Typeof NaN / / returns number

Typeof false / / returns boolean

Typeof [1, 2, 3, 4] / / return to object

Typeof {name:'John', age:34} / / returns object

Typeof new Date () / / returns object

Typeof function () {} / / returns function

Typeof myCar / / returns undefined (if myCar does not declare)

Typeof null / / returns object

Please note:

The data type of NaN is number

The data type of the Array is object

The data type of date (Date) is object

The data type of null is object

The data type of the undefined variable is undefined

If the object is JavaScriptArray or JavaScriptDate, we cannot determine their type by typeof, because they all return object.

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