Does JavaScript convert Array into an Object internally? [duplicate]

Question

I am aware that everything is an object in JavaScript but something struck me when i was using the console of Internet Explorer -F12 (Yes IE, not allowed to use other browsers)

If i type a sample array in the console as:

[1,2]

the output is

1,2{
    0:1,
    1:2
   }

Does this mean that JavaScript converts Array into an Object with keys and values?

Array's are object, so yes or no depending on how you look at it. — dandavis
– dandavis, Commented Feb 25, 2014 at 17:14
Is this really exactly the output you're getting? It doesn't even make any sense — Romain Braun
– Romain Braun, Commented Feb 25, 2014 at 17:14
the output shown is merely a visualization by a graphical debug console... you can log JSON.stringify(arr) if in doubt... — dandavis
– dandavis, Commented Feb 25, 2014 at 17:15
typeof [1,2,3] results in "object" so there is no primitive object type — Ben
– Ben, Commented Feb 25, 2014 at 17:16

Matt Pileggi · Accepted Answer · 2014-02-25 17:16:34Z

3

Yes, arrays in JS are simply objects with numeric keys. You could do the reverse:

var myarray = { 0: 'first', 1: 'second', 2: 'third' };
console.log(myarray[1]);

answered Feb 25, 2014 at 17:16

Matt Pileggi

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3 Comments

dandavis Over a year ago

for some reason that "array"s length property is wrong and [].join doesn't work either... Maybe it's not-so-simple?

Matt Pileggi Over a year ago

Well, Array is a special object so my example does not inherit the Array.prototype. So I guess in that sense it's not the exact same thing. But the OP was asking if the data itself is stored the same way.

dandavis Over a year ago

if the question is is " the data itself is stored the same way", the answer is still no. V8 for example would store the OP's code as an intArray, but an object "equivalent" uses a different data structure altogether.

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