ftst

Fast TypeScript Transpiler

Fast TS transpiler removes types from a typescript file leaving readable javascript. Since generated javascript is line-by-line equivalent to the typescript source this allows to avoid using source maps while debugging.

Installing

npm install ftst

Usage

from command line

node -r ftst filename.ts

JS API

transpileModule(code, options, remove) - analogue of ts function with same name,

Input:

code - typescript code

options - specified compiler options

remove - if set to true generated output will be without commented out types

Output:

result = { outputText: outputText, diagnostics: diagnostics}

outputText - resulting javascript code

diagnostics - array with syntax errors

Example:

var ftst = require("ftst/transpiler");
var options = {
    compilerOptions: {
        newLine: "lf",
        downlevelIteration: true,
        suppressExcessPropertyErrors: true,
        module: ftst.ModuleKind.CommonJS,
        removeComments: false,
        target: ftst.ScriptTarget.ES2020,
        noEmitHelpers: true,
        preserveConstEnums: true,
        noImplicitUseStrict: true
    },
    reportDiagnostics: true
};
let source = 'let decimal: number = 6;';

let result = ftst.transpileModule(source, options, true);

transpile(code, options, remove) - shortcut function for transpileModule; returns only js code without diagnostics

TODO webpack

Requirements

Since the goal is to keep generated javascript readable, only Es2019, Es2020 and EsNext script targets are supported.

Running the Unit Tests

You need to make some preparations for using tests:

1. Download latest version of ts sources from https://github.com/microsoft/TypeScript
2. Create directory for typescripts tests, for example tests, and copy content of tests\cases from ts sources to created dir
3. Use prepare-tests.js from CLI: node test/prepare-tests.js ./tests
4. Now your ready to use tests.

For main tests:

npm test

For Es2019 tests:

npm test test/test-es2019.js

For TSX tests:

npm test test/test-tsx.js