React Native typescript configuration

rn-cli.config.js

var path = require('path');
module.exports = {
  getAssetExts() {
    return [
      'ts',
      'tsx'
    ]
  },
  getTransformModulePath() {
    return path.join(__dirname, 'transformer.js');
  },
}

transformer.js

'use strict';
let path = require('path');
let ts = require('typescript');
let tsConfig = require('./tsconfig.json');
let rnTransform = require('react-native/packager/transformer').transform;

function transform(data, callback) {
	// Do custom transformations
	let result = data.sourceCode;
	if (path.extname(data.filename) == '.tsx' || path.extname(data.filename) == '.ts') {
		try {
			result = ts.transpileModule(result, {compilerOptions: tsConfig.compilerOptions});
			result = result.outputText;
		} catch(e) {
			callback(e);
			return;
		}
	}

	// Pass the transformed source to the original react native transformer
	
	try {
		result = rnTransform(result, data.filename, data.options);
	} catch(e) {
		callback(e);
		return;
	}
	callback(null, result);
}

module.exports = transform;