code: function findConfigFile(filePath) {
  		let prev = null
  		do {
  			const testPath = path.join(filePath, 'tsconfig.json')
  			if (fs.existsSync(testPath)) {
  				return testPath
  			}
  			prev = filePath
  			filePath = path.dirname(filePath)
  		} while (prev !== filePath)
  		return undefined
  	}
docs: Microsoft's ts.findConfigFilepath does not work under Windows (hard coded '/' as directory separator) https://github.com/Microsoft/TypeScript/pull/9625 probably fixes this but is open since July 11th