class Component {
  constructor(component) {
    this.component = component;
  }
  
  read() {
    return this.component.read();
  }
}

class Select {
  constructor(element) {
    this.element = element;
  }
  
  read() {
    return this.element.options[this.element.selectedIndex].value;
  }
}

class Input {
  constructor(element) {
    this.element = element;
  }
  
  read() {
    return this.element.value;
  }
}

class Checkbox {
  constructor(element) {
    this.element = element;
  }
  
  read() {
    return this.element.checked;
  }
}

let take = (selector) => document.querySelector(selector);

let select = new Component(new Select(take('.select')));
let input = new Component(new Input(take('.input')));
let checkbox = new Component(new Checkbox(take('.checkbox')));

let reader = (sources) => sources.map((source) => source.read());

let data = reader([
  select,
  input,
  checkbox
]);

// use data