问题描述
我很好奇它是如何运作这种结构的。当我从Javascript访问navigator.mimetypes时，我正在访问一个对象。
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"
该对象包含对象列表。
navigator.mimeTypes [Object_0，Object_1，Object_2，...]
navigator.mimeTypes[Object_0, Object_1, Object_2, ...]
>>> typeof(navigator.mimeTypes[0])
"object"
例如，我可以检索第一个对象：
For example, I can retrieve the first object:
MimeType { constructor=MimeType, enabledPlugin=Plugin, type="application/x-vnd.google.update3webcontrol.3"}
任何人都可以解释一下为什么这有效吗？
Can anyone explain me why this is working?
>>> navigator.mimeTypes["application/x-shockwave-flash"]
MimeType { constructor=MimeType, type="application/x-shockwave-flash", description="",more...}
我的意思是为什么我能够通过[application / x-shockwave找到指定的对象-flash] ??
I mean why I am able to find the specified object by means of ["application/x-shockwave-flash"] ??
javascript对我来说将是一个新世界：）
javascript will be a new world to me :)
推荐答案
navigator.mimeTypes 返回一个名为的对象MimeTypeArray 它不是传统的JavaScript数组，而是一个对象有类似数组的属性，你可以通过索引或名称访问它的属性。
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.
编辑：当你使用 navigator.mimeTypes ['someType'] 你正在将 MimeTypeArray 视为哈希映射，其中 someType 映射到a MimeType 数组中的对象，该对象还具有与键值相同的类型属性。这是DOM中的一个奇怪的对象（不是技术上的JavaScript），你通常不会看到很多像这样的对象。
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.
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