ttypescript

What it is

Currently TypeScript doesn't support custom transformers in the tsconfig.json, but supports it programmatically.

And there is no way to compile your files using custom transformers using tsc command.

TTypescript (Transformer TypeScript) solves this problem by patching on the fly the compile module to use transformers from tsconfig.json.

How to install

npm i ttypescript -D

ttypescript uses your installed typescript in your node_modules

How to use

tsconfig.json

You just need to add the customTransformers block with before and(or) after object contains array of transformer paths into the compilerOptions.plugins

Don't forget to exclude your transformers in the tsconfig.json

{
    "compilerOptions": {
        "plugins": [
            {
                "customTransformers": {
                    "before": ["transformer-module"],
                    "after": ["./transformers/my-transformer.ts"]
                }
            }
        ]
    },
    "exclude": ["node_modules", "transformers/**/*"]
}

Command line

Like usual tsc, all arguments work the same way.

npx ttsc

Be careful npx ttsc test.ts like tsc test.ts doesn't use your tsconfig.json and transformations won't be applied

ts-node

npx ts-node --compiler ttypescript index.ts
or
npx ts-node -C ttypescript index.ts

Webpack

    {
        test: /\.(ts|tsx)$/,
        include: paths.appSrc,
        loader: require.resolve('ts-loader'),
        options: {
            compiler: 'ttypescript'
        }
    }

VC Code

If you want to compile your project with VC Code task runner you need to overwrite the config typescript.tsdk to path of the installed ttsc:

"typescript.tsdk": "/usr/local/lib/node_modules/ttypescript/lib",
or 
"typescript.tsdk": "node_modules/ttypescript/lib",

Transformers

You can use transformers written in ts or js

As extra feature ttsc provide the program as a second argument

import * as ts from 'typescript';
export default (ctx: ts.TransformationContext, program: ts.Program): ts.Transformer<ts.SourceFile> => {
    return sourceFile => {
        function visitor(node: ts.Node): ts.Node {
            return ts.visitEachChild(node, visitor, ctx);
        }
        return ts.visitNode(sourceFile, visitor);
    };
};

Example

An example project is in the example directory

License

MIT License