Detector for file extensions

ExtensionDetector,ts

/**
 * Detect file extension from filename
 * @param filename
 * @param extension including the dot
 */
export class ExtensionDetector {
    constructor() {
    }

    /**
     * E.g foo.bar ==> .bar
     * @return file extension with .
     * @param filename
     */
    getExtension(filename: string): string {
        const re = /(?:\.([^.]+))?$/
        return  re.exec(filename)![1];
    }

}