js-to-ts-converter

Small utility that I wrote to script converting a JS codebase which contains ES6 classes into TypeScript classes.

The utility does two things:

1. Renames .js files to .ts
2. Adds property declarations to ES6 classes so that they are compilable by the TypeScript compiler (see below).

For #2 above, the utility basically looks at any this property accessed by a JS class, and fills in the appropriate TypeScript property declarations. Take this .js input source file as an example:

class Super {
    someMethod() {
        this.superProp = 1;
    }
}

class Sub extends Super {
    someMethod() {
        this.superProp = 2;
        this.subProp = 2;
    }
}

The above JS classes are replaced with the following TS classes:

class Super {
    public superProp: any;   // <-- added

    someMethod() {
        this.superProp = 1;
    }
}


class Sub extends Super {
    public subProp: any;    // <-- added

    someMethod() {
        this.superProp = 2;
        this.subProp = 2;
    }
}

The goal of this utility was to simply make the .js code compilable under the TypeScript compiler, so simply adding the property declarations typed as any was the quickest option there. The utility may look at property initializers in the future to determine a better type.

Fair Warning

This utility makes modifications to the directory that you pass it. Make sure you are in a clean git (or other VCS) state before running it in case you need to revert!

Running the Utility from the CLI

npm install --global js-to-ts-converter

js-to-ts-converter path/to/js/files

Running the Utility from Node

TypeScript:

import { convertJsToTs, convertJsToTsSync } from 'js-to-ts-converter';


// Async
convertJsToTs( 'path/to/js/files' ).then( 
    () => console.log( 'Done!' ),
    ( err ) => console.log( 'Error: ', err );
); 


// Sync
convertJsToTsSync( 'path/to/js/files' );
console.log( 'Done!' );

JavaScript:

const { convertJsToTs, convertJsToTsSync } = require( 'js-to-ts-converter' );


// Async
convertJsToTs( 'path/to/js/files' ).then( 
    () => console.log( 'Done!' ),
    ( err ) => console.log( 'Error: ', err );
); 


// Sync
convertJsToTsSync( 'path/to/js/files' );
console.log( 'Done!' );

Developing

Make sure you have Node.js installed.

Clone the git repo:

git clone https://github.com/gregjacobs/js-to-ts-converter.git

cd js-to-ts-converter

Install dependencies:

npm install

Run Tests:

npm test