This post talks on how you can parse Typescript code in Java using Eclipse V8 wrapper. Why would one do that? I used it to prepare Javascript documentation for Bedrock, my React component library. I tried using both React Styleguidist and Storybook but haven’t liked both (will discuss those reasons in a later post).

Parsing means generating an Abstract Syntax Tree from the TS source code. Once you have the AST you can crawl it, to run any transform or aggregation as you like.

Let’s start by creating a new V8 instance that also understands the NodeJS runtime

NodeJS nodeJS = NodeJS.createNodeJS();

Next step is to load the Typescript parser in V8 using require. I am using the entire folder from a previously existing node_modules folder.

V8Object typescript = nodeJS.require(new File("path_to/node_modules/typescript"));

Now we need to obtain the Typescript.ScriptTarget.Latest value. This value allows us to instruct TS compiler to use latest TS syntax guidelines during the parsing phase.

V8Object moduleKind = typescript.getObject("ScriptTarget");
Integer system = moduleKind.getInteger("Latest");

Next, we need to setup compiler options. These shall be needed in the next step.

V8Object compilerOptions = new V8Object(nodeJS.getRuntime());
compilerOptions.add("module", system);

Before we invoke the parser, let’s load the TS source code in memory from the file on disk.

String code ="my-ts-file.ts");

Finally time to invoke the TS compiler:

V8Object result = (V8Object) typescript.executeJSFunction("createSourceFile", fileName, code, compilerOptions, true);

Iterating over the V8Object is difficult, so we will use a utility method to convert it to normal java.util.Map

Map<String, ? super Object> astAsMap = V8ObjectUtils.toMap(result);

And that is all what we need. You may now use astAsMap to crawl/iterate over the AST as your use-case desire. But before, we wrap it up here, we need to clean up the resources that V8 allocated:

while (nodeJS.isRunning()) {

// release all resources

You can find all the code together in this Github repository including conversion to strongly typed Java objects.