This is old project for TypeScript, which is developing so fast. I think now is not the best option for parsing TypeScript. Now it's not easy to upgrade to the current TypeScript. For JavaScript I think it still good. It's time to rewrite TypeScriptAST. Microsoft showed us how to do it in System.Text.Json for .NET Core 3.0: "Provide high-performance JSON APIs. We needed a new set of JSON APIs that are highly tuned for performance by using Span" https://devblogs.microsoft.com/dotnet/try-the-new-system-text-json-apis/ https://github.com/dotnet/runtime/blob/master/src/libraries/System.Text.Json/src/System/Text/Json/Reader/Utf8JsonReader.cs

TypeScriptAST

.NET port of Microsoft's TypeScript parser for simple AST manipulation.

It works with TypeScript, JavaScript and DefinitelyTyped(".d.ts") files and gives the same tree as typescriptServices.js.

Install TypeScriptAST via NuGet

If you want to include TypeScriptAST in your project, you can install it directly from NuGet

PM> Install-Package TypeScriptAST

Create AST

var ast = new TypeScriptAST(File.ReadAllText(file), file);

Find Node

By SyntaxKind

  var functions = ast.OfKind(SyntaxKind.FunctionExpression);
  var vars = functions.FirstOrDefault()?.OfKind(SyntaxKind.VariableDeclaration);

By Node type

  var functions = ast.GetDescendants().OfType<FunctionExpression>();
  var vars = functions.FirstOrDefault()?.GetDescendants().OfType<VariableDeclaration>();

GetText

  var firstFunc = ast.OfKind(SyntaxKind.FunctionExpression).FirstOrDefault();
  var text = firstFunc?.GetText();
  var withComments = firstFunc?.GetTextWithComments();

Change Node

  var funcNewCode = "function() {}";
  var change = new ChangeAST();
  change.ChangeNode(firstFunc, funcNewCode);
  var newSource = change.GetChangedSource(ast.SourceStr);
  File.WriteAllText(file, newSource);

File modification Example

This example included in TypeScriptAstExample. It finds modules in file, collects some info, adds new function to module.

  using Zu.TypeScript;
  using Zu.TypeScript.Change;
  using Zu.TypeScript.TsTypes;
  
            var fileName = "parser.ts";
            var source = File.ReadAllText(fileName);

            var ast = new TypeScriptAST(source, fileName);

            var change = new ChangeAST();

            foreach (var module in ast.GetDescendants().OfType<ModuleDeclaration>())
            {
                var funcs = module.Body.Children.OfType<FunctionDeclaration>().ToList();
                var enums = module.Body.Children.OfType<EnumDeclaration>();
                var moduleInfoFunc = $@"
    export function getModuleInfo() {{
        return ""Module {module.IdentifierStr} contains {funcs.Count()} functions ({funcs.Count(v => v.IdentifierStr.StartsWith("parse"))} starts with parse), {enums.Count()} enums ..."";
    }}
";
                change.InsertBefore(module.Body.Children.First(), moduleInfoFunc);
            }
            var newSource = change.GetChangedSource(ast.SourceStr);

            File.WriteAllText("parser2.ts", newSource);