Array is not a data type in Javascript? - Stack Overflow

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According to Professional Javascript for Web developers array is not a datatype in Javascript:

❑   “undefined” if the value is undefined 
❑   “boolean” if the value is a Boolean 
❑   “string” if the value is a string 
❑   “number” if the value is a number
❑   “object” if the value is an object or null 
❑   “function” if the value is a function

Is that correct?

According to Professional Javascript for Web developers array is not a datatype in Javascript:

❑   “undefined” if the value is undefined 
❑   “boolean” if the value is a Boolean 
❑   “string” if the value is a string 
❑   “number” if the value is a number
❑   “object” if the value is an object or null 
❑   “function” if the value is a function

Is that correct?

• javascript
• arrays
• types

Share Improve this question Follow edited Nov 10, 2010 at 19:30 BoltClock 724k165165 gold badges1.4k1.4k silver badges1.4k1.4k bronze badges asked Nov 10, 2010 at 19:27 ajsieajsie 79.8k110110 gold badges284284 silver badges386386 bronze badges

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5 Answers 5

Sorted by: Reset to default 5

This is correct, Array is just a descendant of object. Note though it does override a few things, for example .toString() in an array prints it's members in a ma list, instead of "[Object object]" like a plain object would.

I believe that is because an "Array" is an "object"

http://jsfiddle/z5Gv2/

As others say it's treated as "object". You can test for an object being an array by checking if its constructor is === to Array.

yes , Array is not a data type in JavaScript. The set of types in JavaScript are of Primitive values and Objects.

So Array falls under the category of Objects.

Arrays are not a data type in Javascript because under the hood they are objects with key:value pairs. Where the keys are the index and values are the array content. For example

let example = ["a","b","c","d","e"]

is the same as an object representation

let example = {
0: "a",
1: "b",
2: "c",
3: "d",
4: "e"
};

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