typeof(array)===object和如何判断array & object 的问题

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上篇留了个遗留问题 typeof([]) // object ，如果typeof将array返回的是object那我们要怎么判断，传进来的变量array和object呢？
下面来走进…JS。

type([])

在JavaScript的数据结构中有提到
JS有7种数据类型

The latest ECMAScript standard defines seven data types:
Six data types that are primitives(原始类型):
Boolean
Null
Undefined
Number
String
Symbol (new in ECMAScript 6)
and Object(对象类型)

而typeof这个方法返回的是原始类型，或者object

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Undefined	"undefined"
Null	"object" (Null返回object比较特殊，是个历史遗留问题，这个不管它)
Boolean	"boolean"
Number	"number"
String	"string"
Symbol (new in ECMAScript 2015)	"symbol"
Host object (provided by the JS environment)	Implementation-dependent
Function object (implements [[Call]] in ECMA-262 terms)	"function"
Any other object	"object"

为啥typeof(array)等于object也有了解释
Arrays are regular objects for which there is a particular relationship between integer-key-ed properties and the ‘length’ property. Additionally, arrays inherit from Array.prototype which provides to them a handful of convenient methods to manipulate arrays. For example, indexOf (searching a value in the array) or push (adding an element to the array), etc. This makes Arrays a perfect candidate to represent lists or sets.
array其实并不是JS标准的7种类型，只算是object的一种。

判断 Array Object

两种方法

  • Array.isArray (对老浏览器，可能有兼容性问题)
  • Object.prototype.toString.call()

好了，这篇就到这了，希望能让看客老爷有些收获，感谢阅读！