为何库的主对象常以大写字母开头？以Backbone.js为例

Great question—this is a super common point of confusion for developers new to Backbone and JavaScript library design conventions! Let’s break down why this choice makes sense, even if it feels different from your everyday code:

• It aligns with constructor/namespace naming conventions
  Even though you won’t typically new Backbone() directly (it acts more like a namespace than a single constructor), the capitalized name signals this is the root of a library full of constructor functions. Think about core components like Backbone.Model, Backbone.View, and Backbone.Router—every one of these is a constructor you do instantiate with new. Using a capitalized root keeps the entire API consistent: you instantly recognize anything under Backbone is either a constructor or a core library utility, not a random helper variable.

• It distinguishes library APIs from regular code variables
  In your everyday code, you’d write something like var person = new Person("John")—here, Person (capitalized) is the constructor, and person (lowercase) is the instance. Backbone isn’t an instance though—it’s the top-level entry point to the framework. Capitalizing it makes it immediately clear this is a special, library-owned object, not a variable you declared in your app. This avoids naming collisions and makes code faster to scan.

• It’s a deliberate choice for API clarity
  Early JavaScript libraries leaned into clear, recognizable naming to guide developers. Backbone’s creator chose the capitalized Backbone to emphasize that this is the structural "backbone" of your application—an authoritative container for all the framework’s building blocks. Even if some parts use factory-style patterns, the capitalized name keeps the API predictable and aligned with how developers expect constructor-focused libraries to behave.

To sum it up: the capitalized Backbone is less about whether it’s a direct constructor or factory, and more about building a consistent, intuitive API that signals "this is the core of the framework—use it to access all the tools you need."

内容的提问来源于stack exchange，提问作者Artem