[ES6] Object.assign (with defaults value object)

function spinner(target, options = {}){

  let defaults = {
    message: "Please wait",
    spinningSpeed: 5,
    cssClass: ".is-spinning"
  };

  let settings = Object.assign(
    {},
    defaults,
    options
  );

  if(settings.spinningSpeed !== defaults.spinningSpeed){
    settings.cssClass = _addSpeedClass(target);
  }

  _renderSpinner(target, settings);
}

• Best pratices to write defaults as an objects, much clean and reuseable.
• Write an empty object {} to the object.assign is recommened, it avoid defaults been mutated.
• in if block, you see we might still use default value, so it is important to keep the origin defautls value.

Example2:

function spinner(target, options = {}) {
  let defaults = {
    message: "Please wait",
    spinningSpeed: 5,
    cssClass: ".is-spinning"
  };

  let settings = Object.assign({} , defaults , options);

  console.log(`Message: ${settings.message}`);
  console.log(`spinningSpeed: ${settings.spinningSpeed}`);
  console.log(`cssClass: ${settings.cssClass}`);
}

spinner(targetElement, {
  cssClass: ".is-fast-spinning", 
  spinningSpeed: 8 
});