Question

I’m curious about how it is working this structure. When I’m accesing the navigator.mimetypes from Javascript I’m accesing an object.

>>> typeof(navigator.mimeTypes)
"object"

That object has list of objects.

navigator.mimeTypes[Object_0, Object_1, Object_2, …]

>>> typeof(navigator.mimeTypes[0])
"object"

For example, I can retrieve the first object:

navigator.mimeTypes[0]

MimeType { constructor=MimeType, enabledPlugin=Plugin, type="application/x-vnd.google.update3webcontrol.3"}

Can anyone explain me why this is working?

>>> navigator.mimeTypes["application/x-shockwave-flash"]

MimeType { constructor=MimeType, type="application/x-shockwave-flash", description="",more...}

I mean why I am able to find the specified object by means of [“application/x-shockwave-flash”] ??

javascript will be a new world to me 🙂

Answer 1

navigator.mimeTypes returns an object called MimeTypeArray it’s not a traditional JavaScript array but an object that had Array like properties, you can access it’s properties either by index or name.

edit: When you use navigator.mimeTypes['someType'] you’re treating the MimeTypeArray like a hash map, that has someType mapped to a MimeType object in the array that also has a type property of the same value as the key. This is a strange object in the DOM (not technically JavaScript) and you don’t typically see many objects like this.