attach-events decorator for react

attach-events.js

/**
 * @decorator
 * Attach events to DOM element
 *
 * @param {Element|Function} elemOrFunc: DOM Element, or a function returns element
 * @param {String} events: a list events separated with ','
 * @param {String} preventDecorator: prevent decorate when it doesn't need
 *
 * Usage:
 *   @attachEvents(window, 'click')
 *   handleWindowClick(evt) {
 *     ...
 *   }
 * 
 *   @attachEvents(window, 'resize', IS_MOBILE)
 *   handleWindowClick(evt) {
 *     ...
 *   }
 *
 *   @attachEvents(document, 'mousedown, touchstart')
 *   handlePointerDown(evt) {
 *     ...
 *   }
 *
 *   @attachEvents(function getElem() { return this.refs.elem; }, 'click')
 *   handleClickOnElem(evt) {
 *     ...
 *   }
 */

const noop = () => {};

export function attachEvents(elemOrFunc, events, preventDecorate) {
  if (preventDecorate) return function (target, key, descriptor) { return descriptor; };
  
  const eventList = events.split(/\s*,\s*/);
  const getElem = typeof elemOrFunc === 'function' ? elemOrFunc : () => elemOrFunc;

  return function decorator(proto, method, descriptor) {
    const {
      componentDidMount = noop,
      componentWillUnmount = noop,
    } = proto;

    const symbolHandler = Symbol(method);

    function addListener() {
      const elem = getElem.call(this);

      const handler = this[symbolHandler] = (...args) => {
        descriptor.value.apply(this, args);
      };

      eventList.forEach((evt) => {
        elem.addEventListener(evt, handler);
      });
    }

    function removeListener() {
      const elem = getElem.call(this);

      eventList.forEach((evt) => {
        elem.removeEventListener(evt, this[symbolHandler]);
      });
    }

    // eslint-disable-next-line no-param-reassign
    proto.componentDidMount = function componentDidMountWrapped() {
      componentDidMount.call(this);

      addListener.call(this);
    };

    // eslint-disable-next-line no-param-reassign
    proto.componentWillUnmount = function componentWillUnmountWrapped() {
      componentWillUnmount.call(this);

      removeListener.call(this);
    };
  };
}