This blog is a part of my TypeScript series, and the previous ones are: 1. Why program in TypeScript 2. Structural vs nominal typing 3. Getting started with TypeScript classes TypeScript includes the keywords public, protected, and private to control access to the members of a class i.e. Properties or methods. Jun 18, 2018 We can prefix the constructor parameters with the public or private keyword to automatically have TypeScript assign the parameter as a property of the class. In this example, this removes the unnecessary declaration and assignment of both firstName and lastName. Abstract classes and methods can be created using abstract keyword within the abstract class. Unlike interface: An abstract class can give implementation details for its members. An abstract class allows to marks its members methods as private and protected. TypeScript Getter and Setter Property Example.
TypeDoc runs the TypeScript compiler and extracts type information from the generated compiler symbols.Therefore you don’t have to include additional metadata within your comments, TypeScript specific elementslike classes, enumerations or property types and access modifiers will be automatically detected.
# Comment Parsing
# Markdown
All comments are parsed as markdown. TypeDoc uses the Marked markdown parserto convert comments to HTML.
# Code Blocks
TypeDoc supports code blocks in markdown and uses HighlightJSto provide syntax highlighting. HighlightJS will auto detect the language for code blocks, howeveryou can also explicitly specify the language.
# Symbol References
You can link to other classes, members or functions using double square brackets or an inline link tag.
Links may also specify their link text by including a pipe (
|
) character after the name.Links are resolved by looking at child reflections, then at adjacent reflections, then at parent reflections.If a name contains a dot (
.
), each part of the name will be treated as the name of a reflection.For example, to link to the member
property of Foo
, you can use {@link Foo.member}
. For more detailson link resolution see the Link Resolution guide.# Supported tags
TypeDoc supports a specific set of tags. Many JSDoc tags are not supported because the TypeScriptcompiler can infer the information directly from code. TypeDoc renders any unsupported tags in alist in the documentation, so they are not lost.
When writing documentation for function signatures, you don’t have to repeat yourself. TypeDoc automaticallycopies comments and tags of the function implementation to its signatures for you. Of course you can stilloverwrite them if you wish to. Font addon wow classic.
The documentation generator currently understands the following doc comment tags:
#@param <param name>
Documents a parameter for the subsequent method specified by the param name. The JSDoc param typeis not necessary because it will be read from the TypeScript types.
#@typeParam <param name>
Documents a generic type parameter for the subsequent symbol specified by the param name.
#@return(s)
Documents the return of the subsequent method
#@event
Documents events triggered by the subsequent method
#@hidden and @ignore
![Typescript Abstract Property Typescript Abstract Property](https://resources.jetbrains.com/help/img/dotnet/2020.1/generate_properties_typescript.png)
Keeps the subsequent code from being documented.
#@internal
Marks the following code as internal.If the TypeScript
--stripInternal
compiler flag is passed, TypeDoc will not document the given code.#@category
Allows grouping reflections on a page
# Namespaces
![Abstract Abstract](https://resources.jetbrains.com/help/img/idea/2020.2/ws_ts_refactoring_pull_members_up.png)
Namespaces (previously referred to as “modules”) can be commented like any other elements in TypeScript. As namespaces can be defined in multiplefiles, TypeDoc selects the longest comment by default. One may override this behavior with the special
@preferred
comment tag. Kinesis freestyle program keys for mac.# Files
A doc comment describing a file must be placed before any code in the file.It should be annotated with the
@packageDocumentation
tag so that TypeDoc knows that it is intended to be documentation for the file itself.- Document your code
- Comment Parsing
- Supported tags
If you are doing traditional OOP with TypeScript, the structural features of TypeScript mightsometimes get in your way. Look at the following class hierachy for instance:
The
FilterItem
abstract class needs to be implemented by other classes. In this example byAFilter
and BFilter
. So far, so good. Classical typing works like you are used to fromJava or C#:When we need the structural information, though, we leave the realms of traditional OOP.Let’s say we want to instantiate new filters based on some token we get from an AJAX call.To make it easier for us to select the filter, we store all possible filters in a map:
The map’s generics are set to a string (for the token from the backend), and everythingthat complements the type signature of
FilterItem
. We use the typeof
keyword hereto be able to add classes to the map, not objects. We want to instantiate them afterwards,after all.So far everything works like you would expect. The problem occurs when you want tofetch a class from the map and create a new object with it.
What a problem! TypeScript only knows at this point that we get a
FilterItem
back,and we can’t instantiate FilterItem
. Since abstract classes mix type information andactualy language (something that I try to avoid), a possible solution is to move tointerfaces to define the actual type signature, and be able to create properinstances afterwards:Note the
new
keyword. This is a way for TypeScript to define the type signatureof a constructor function.Lots of ?s start appearing now. No matter where you put the
implements IFilter
command, no implementation seems to satisfy our contract:What’s happening here? Seems like neither the implementation, nor theclass itself seem to be able to get all the properties and functionswe’ve defined in our interface declaration. Why?
JavaScript classes are special: They have not only one type we could easilydefine, but two types! The type of the static side, and the type of the instanceside. It might get clearer if we transpile our class to what it was before ES6:a constructor function and a prototype:
One type to create the object. One type for the object itself. So let’s splitit up and create two type declarations for it:
The first type
FilterConstructor
is the constructor interface. Here are all static properties,and the constructor function itself. The constructor function returns an instance: IFilter
.IFilter
contains type information of the instance side. All the functions we declare.By splitting this up, our subsequent typings also become a lot clearer:
- We add
FilterConstructor
s to our map. This means we only can add classes thatprocude the desired objects. - What we want in the end is an instance of
IFilter
. This is what the constructorfunction returns when being called withnew
.
Our code compiles again and we get all the auto completion and tooling we desire.Even better: We are not able to add abstract classes to the map. Because they don’tprocude a valid instance:
Typescript Virtual Method
Traditional OOP, weaved in into our lovely type system. ✅
Typescript Abstract Static
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