const withFont = (fontName) => {
    let font = null;
    getFont(fontName).then(f => font = f);
    
    return class Text {
        getFont() {
            return font;
        }
    };
};

const RobotoText = withFont('Roboto');

new RobotoText().getFont();

const servlet = (qs = '') => new Promise((resolve) => $.get(`myservlet${qs}`, {}, resolve, 'json'))

const chain = (data) => servlet(`?chain=${data.expected}`)

const tap = (effect) => (data) => {
    effect(data)
    return data
}

const show = (data) => console.info(data)

const logger = ({ steps }) => console.log(`Number of steps advanced is ${steps}`)

servlet()
    .then(tap(show))
    .then(chain)
    .then(tap(show))
    .then(chain)
    .then(tap(show))
    .then(chain)
    .then(tap(show))
    .then(chain)
    .then(tap(logger))
    .then(tap(show))

const hover = (elements, enter, leave = enter) => [ ...elements ]
  .forEach((element) => [['mouseenter', enter], ['mouseleave', leave]]
  .forEach(([ ...params ]) => element.addEventListener(...params)))

// use
hover(document.querySelectorAll('button'), () => console.log('enter'), () => console.log('leave'))

const hover = (elements, enter, leave = enter) => [ ...elements ]
  .forEach((element) => [['mouseenter', enter], ['mouseleave', leave]]
  .forEach(([ ...params ]) => element.addEventListener(...params)))

// use
hover(document.querySelectorAll('button'), () => console.log('enter'), () => console.log('leave'))