CodeDOM in .NET (Framework) has come with 3 providers:

1. CSharpCodeProvider
2. VBCodeProvider
3. JScriptCodeProvider

While JSCriptCodeProvider is good enough for generating JavaScript codes for Internet Explorer however IE had been discoutinued. TypeScriptCodeProvider provides extra benefits over a "JavaScript Provider" through generating TypeScript codes:

1. Strongly typed interfaces and function prototypes for validation during design time and compile time.
2. Re-use some portions of CodeDOM codes if a code generator toolset like WebApiClientGen and OpenApiClientGen targets multiple OO languages and multiple TypeScript libraries/frameworks.
3. Naturally and inheriently adapt the evolution of the JavaScript standard as long as TypeScript will.
4. Live well with TypeScript frameworks like Angular 2+ and Aurelia. And with Angular Reactive Forms, runtime validation could become possible, similar to the use cases of using validation attributes to decorate a member property of a .NET class.

Nuget package:

• Fonlow.TypeScriptCodeDomCore

What For and Not

TypeScript CodeDOM is for code generators that use CodeDOM over template or Roslyn, for example, Fonlow.Poco2TS that reads an assembly with POCO classes, and WebApiClientGen that reads assemblies and the run time type info of a running Web API, and then create Code DOM that could be used to generate C# and TypeScript codes.

There are scenarios that Roslyn and template may provide more powerful features that you want and help you to write less codes with simpler design when developing the code generators.

What Supported and Not

CodeDOM covers almost every essential C# language features, however, not every features of such coverage is applicable to TypeScript.

GeneratorSupport Enum

bool ICodeGenerator.Supports(GeneratorSupport supports)
{
	return (supports & supported) != 0;
}

const GeneratorSupport supported = GeneratorSupport.ArraysOfArrays
	| GeneratorSupport.MultidimensionalArrays
	| GeneratorSupport.TryCatchStatements
	| GeneratorSupport.DeclareValueTypes
	| GeneratorSupport.DeclareEnums
	| GeneratorSupport.StaticConstructors
	| GeneratorSupport.DeclareInterfaces
	| GeneratorSupport.DeclareDelegates
	| GeneratorSupport.NestedTypes
	| GeneratorSupport.MultipleInterfaceMembers
	| GeneratorSupport.ComplexExpressions
	| GeneratorSupport.GenericTypeReference
	| GeneratorSupport.GenericTypeDeclaration
   ;

Supported CodeDOM Classes

Most supported classes are covered by unit testing, while some are covered by integration testing in some code generator projects, marked as "Indirectly" in the table below.

Class	Unit Tests
CodeArgumentReferenceExpression	TestCodeArgumentReferenceExpression
CodeArrayCreateExpression	TestCodeArrayCreateExpression*
CodeArrayIndexerExpression	TestCodeArrayIndexerExpression*
CodeAssignStatement	TestCodeAssignStatement
CodeAttributeDeclaration / CodeAttributeDeclarationCollection	Test*Decorators
CodeAttributeArgument / CodeAttributeArgumentCollection	Indirectly
CodeBaseReferenceExpression	TestCodeBaseReferenceExpression
CodeBinaryOperatorExpression	TestCodeIterationStatement
CodeBinaryOperatorType	TestCodeIterationStatement
CodeCastExpression	TestCodeCastExpression
CodeCatchClause / CodeCatchClauseCollection	TestCodeTryCatchFinallyStatement, TestCodeTryCatchFinallyStatement
CodeCommentStatement / CodeCommentStatementCollection	TestCodeCommentStatement*
CodeCompileUnit	Indirectly
CodeConditionStatement	TestCodeConditionStatement*
CodeConstructor	Indirectly
CodeDirective / CodeDirectiveCollection	Indirectly with CodeRegionDirective
CodeTypeDelegate	TestCodeTypeDelegate
CodeExpressionStatement	TestCodeIterationStatement
CodeExpression	TestCodeExpression
CodeExpressionCollection	Indirectly
CodeFieldReferenceExpression	TestCodeFieldReferenceExpression
CodeIndexerExpression	TestCodeIterationStatement
CodeIterationStatement	TestCodeIterationStatement
CodeMemberField	TestCodeTypeDeclarationWithMembers
CodeMemberMethod	TestCodeTypeDeclarationWithMethodAndParameterDecorators
CodeMemberProperty	TestCodeTypeDeclarationWithPropertyMembers
CodeMethodInvokeExpression	TestCodeIterationStatement, TestCodeTryCatchFinallyStatement, TestCodeTryCatchStatement
CodeMethodReferenceExpression	TestCodeMethodReferenceExpression, TestCodeMethodReferenceExpressionGeneric, TestCodeIterationStatement
CodeMethodReturnStatement	TestCodeMethodReturnStatement
CodeNamespace / CodeNamespaceCollection	Indirectly
CodeObject	Indirectly in many derived classes
CodeObjectCreateExpression	TestCodeObjectCreateExpression*
CodeParameterDeclarationExpression / CodeParameterDeclarationExpressionCollection	TestTuple4Callback, TestTupleCallbackSnipet, TestTupleCallbackSnipet, TestCodeParameterDeclarationExpression
CodePrimitiveExpression	TestCodeArrayCreateExpressionWithInit, and many
CodePropertyReferenceExpression	TestCodePropertyReferenceExpression
CodeRegionDirective	TestPersonWithRegions, Test2TypesWithRegions
CodeSnippetExpression	TestCodeArrayIndexerExpression, and many
CodeSnippetStatement	TestCodeConditionStatement, and many
CodeSnippetTypeMember	Indirectly
CodeStatement / CodeStatementCollection	TestCodeConditionStatementElse, and many
CodeThisReferenceExpression	TestCodePropertyReferenceExpression, and many
CodeThrowExceptionStatement	TestCodeThrowExceptionStatement
CodeTryCatchFinallyStatement	TestCodeTryCatchFinallyStatement, TestCodeTryFinallyStatement, TestCodeTryCatchStatement
CodeTypeDeclaration	TestCodeTypeDeclaration*
CodeTypeDeclarationCollection	Indirectly with namespace.Types
CodeTypeMember / CodeTypeMemberCollection	Indirectly
CodeTypeOfExpression	TestCodeTypeOfExpression
CodeTypeParameter / CodeTypeParameterCollection	Indirectly
CodeTypeReference / CodeTypeReferenceCollection	TestCodeArrayCreateExpressionWithoutInit, and many
CodeTypeReferenceExpression	TestCodeTypeReferenceExpression, TestCodeIterationStatement
CodeVariableDeclarationStatement	TestCodeVariableDeclarationStatement*
CodeVariableReferenceExpression	TestCodeVariableReferenceExpression, and many

Hints:

• There are integration tests in PocoToTS, WebApiClientGen and OpenApiClientGen, covering some classes like XxxCollection.

Examples Utilizing TypeScriptProvider

• Unit Testing
• Integration Testing with PocoToTS
• Code Generator for Angular Reactive Forms

Generated Code Examples

• Client API codes with typed forms and validators generated from Web API
• OpenAPI to Angular 5+ and integration tests for pet.yaml
• OpenAPI to Angular Reactive Typed Forms
• OpenAPI to Aurelia and integration tests for pet.yaml
• OpenAPI to AXIOS and integration tests for pet.yaml
• OpenAPI to Fetch API and integration tests for pet.yaml
• OpenAPI to jQuery and integration tests for pet.yaml

TypeScript Code Generators

• Nuget package Strongly Typed Web API Client Generators and its plugins for JavaScript libraries and frameworks: jQuery, FetchAPI, AXIOS, Aurelia, Angular 2+, Angular Reactive Forms.
• Command Line Program Strongly Typed OpenAPI Client Generators whic also generates codes for Angular 2+, Angular Reactive Forms, Aurelia, AXIOS, FetchAPI and jQuery.

CodeDOM Features Applicable to TypeScript but not Supported in TypeScriptProvider

• CodeComment
• CodeGotoStatement
• CodeLabeledStatement

CodeDOM Features Not Applicable to TypeScript

• CodeAttachEventStatement
• CodeChecksumPragma
• CodeDefaultValueExpression
• CodeDelegateCreateExpression
• CodeDelegateInvokeExpression
• CodeDirectionExpression
• CodeEntryPointMethod
• CodeEventReferenceExpression
• CodeLinePragma
• CodeMemberEvent
• CodeNamespaceImport
• CodeNamespaceImportCollection
• CodePropertySetValueReferenceExpression
• CodeRemoveEventStatement
• CodeSnippetCompileUnit
• CodeTypeConstructor . Alternative.

History

TypeScript CodeDOM had been a by-product of Strongly Typed Web API Client Generators since October 2015 until February 2024, as a foundation library of TypeScript code generators of WebApiClientGen and then OpenApiClientGen, as well as internal code generators in some companies in which the development teams have chosen the CodeDOM approach over templates.

Legacy repositories:

• Fonlow.TypeScriptCodeDom for .NET Framework and its Nuget package.
• Fonlow.TypeScriptCodeDomCore in WebApiClientGen