TypeScript：接口 vs 类 vs 模块 vs 程序 vs 函数
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TypeScript: Interface vs Class vs Modules vs Program vs Function
提问by Nil Pun
I read the TypeScript specification located at: http://www.typescriptlang.org/Content/TypeScript%20Language%20Specification.pdf
我阅读了位于以下位置的 TypeScript 规范：http://www.typescriptlang.org/Content/TypeScript%20Language%20Specification.pdf
However it got me confused with following:
然而，它让我对以下内容感到困惑：
- Interface
- Class
- Modules
- Programs
- Functions.
- Declare vs. var
- 界面
- 班级
- 模块
- 程式
- 职能。
- 声明与 var
Could someone briefly help to understand which one of above should be used when? Is Interface and Class same as C# version?
有人可以简要地帮助理解什么时候应该使用上述哪一个？接口和类是否与 C# 版本相同？
回答by Fenton
I have made these answers match C# as you've mentioned that in your question, but hopefully the answers are useful to people coming to TypeScript from similar languages too.
正如您在问题中提到的那样，我已经使这些答案与 C# 匹配，但希望这些答案对从类似语言来到 TypeScript 的人也有用。
Interface
界面
An interface in TypeScript is similar to those you have come across in C#. It is a contract - if one of your classes implements an interface, it promises to have certain properties or methods that the interface documents.
TypeScript 中的接口类似于您在 C# 中遇到的接口。它是一种契约——如果你的一个类实现了一个接口，它承诺具有接口记录的某些属性或方法。
In TypeScript an interface can inherit from another interface in order to extend it and from a class to capture its implementation.
在 TypeScript 中，接口可以从另一个接口继承以扩展它，也可以从类继承以捕获其实现。
Whenever something seems impossible in TypeScript, you can usually solve it with an interface!
每当在 TypeScript 中有些事情似乎不可能时，您通常可以使用接口来解决它！
In TypeScript, interfaces have a broad range of uses. They describe a structure, so can be used anywhere you use a type (i.e. not just to implement them in a class, you can use them to type variables, parameters, return values and so on).
在 TypeScript 中，接口有广泛的用途。它们描述了一个结构，因此可以在任何使用类型的地方使用（即不仅可以在类中实现它们，还可以使用它们来键入变量、参数、返回值等）。
Class
班级
This is very similar to the concept of a class in C#. You can inherit from other classes to extend or specialise the behaviour.
这与 C# 中类的概念非常相似。您可以从其他类继承以扩展或专门化行为。
Namespace
命名空间
The newer namespace keyword is used to place a group of code within a limited scope. This is similar to C# namespaces.
较新的命名空间关键字用于在有限范围内放置一组代码。这类似于 C# 命名空间。
Module
模块
Modules are better than namespaces when it comes to TypeScript. A module (previously known as an external module) is a file that is self contained and adds nothing to your global scope. You can load modules into local variables as you need them. Modules provide a good way to organise your code and load parts on demand. When using modules, it is best to avoid using namespaces. Modules are better than namespaces.
就 TypeScript 而言，模块比命名空间更好。模块（以前称为外部模块）是一个自包含的文件，不向全局范围添加任何内容。您可以根据需要将模块加载到局部变量中。模块提供了一种组织代码和按需加载部分的好方法。使用模块时，最好避免使用命名空间。模块比命名空间更好。
Program
程序
A program is a collection of modules, classes. This is essentially the thing you have written using TypeScript.
程序是模块、类的集合。这基本上是您使用 TypeScript 编写的内容。
Function / Method
功能/方法
Classes contain methods, and you can also write stand-alone functions that do not belong to a class.
类包含方法，您还可以编写不属于类的独立函数。
Declare vs. var
声明与 var
varcreates a new variable. declareis used to tell TypeScript that the variable has been created elsewhere. If you use declare, nothing is added to the JavaScript that is generated - it is simply a hint to the compiler.
var创建一个新变量。declare用于告诉 TypeScript 该变量已在别处创建。如果使用declare，则不会向生成的 JavaScript 添加任何内容 - 它只是对编译器的提示。
For example, if you use an external script that defines var externalModule, you would use declare var externalModuleto hint to the TypeScript compiler that externalModulehas already been set up.
例如，如果您使用定义 的外部脚本var externalModule，您将使用declare var externalModule提示externalModule已设置的 TypeScript 编译器。
