react-scroll-captor/lib/ScrollCaptor.js

A component that confines scroll events to its immediate child. Great for dropdown menus etc.

'use strict';

Object.defineProperty(exports, "__esModule", {
  value: true
});

var _createClass = function () { function defineProperties(target, props) { for (var i = 0; i < props.length; i++) { var descriptor = props[i]; descriptor.enumerable = descriptor.enumerable || false; descriptor.configurable = true; if ("value" in descriptor) descriptor.writable = true; Object.defineProperty(target, descriptor.key, descriptor); } } return function (Constructor, protoProps, staticProps) { if (protoProps) defineProperties(Constructor.prototype, protoProps); if (staticProps) defineProperties(Constructor, staticProps); return Constructor; }; }();

var _react = require('react');

var _react2 = _interopRequireDefault(_react);

var _reactNodeResolver = require('react-node-resolver');

var _reactNodeResolver2 = _interopRequireDefault(_reactNodeResolver);

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }

function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }

function _possibleConstructorReturn(self, call) { if (!self) { throw new ReferenceError("this hasn't been initialised - super() hasn't been called"); } return call && (typeof call === "object" || typeof call === "function") ? call : self; }

function _inherits(subClass, superClass) { if (typeof superClass !== "function" && superClass !== null) { throw new TypeError("Super expression must either be null or a function, not " + typeof superClass); } subClass.prototype = Object.create(superClass && superClass.prototype, { constructor: { value: subClass, enumerable: false, writable: true, configurable: true } }); if (superClass) Object.setPrototypeOf ? Object.setPrototypeOf(subClass, superClass) : subClass.__proto__ = superClass; }

var ScrollCaptor = function (_Component) {
  _inherits(ScrollCaptor, _Component);

  function ScrollCaptor() {
    var _ref;

    var _temp, _this, _ret;

    _classCallCheck(this, ScrollCaptor);

    for (var _len = arguments.length, args = Array(_len), _key = 0; _key < _len; _key++) {
      args[_key] = arguments[_key];
    }

    return _ret = (_temp = (_this = _possibleConstructorReturn(this, (_ref = ScrollCaptor.__proto__ || Object.getPrototypeOf(ScrollCaptor)).call.apply(_ref, [this].concat(args))), _this), _this.isBottom = false, _this.isTop = false, _this.cancelScroll = function (event) {
      event.preventDefault();
      event.stopPropagation();
    }, _this.handleEventDelta = function (event, delta) {
      var _this$props = _this.props,
          onBottomArrive = _this$props.onBottomArrive,
          onBottomLeave = _this$props.onBottomLeave,
          onTopArrive = _this$props.onTopArrive,
          onTopLeave = _this$props.onTopLeave;
      var _this$scrollTarget = _this.scrollTarget,
          scrollTop = _this$scrollTarget.scrollTop,
          scrollHeight = _this$scrollTarget.scrollHeight,
          clientHeight = _this$scrollTarget.clientHeight;

      var target = _this.scrollTarget;
      var isDeltaPositive = delta > 0;
      var availableScroll = scrollHeight - clientHeight - scrollTop;
      var shouldCancelScroll = false;

      // reset bottom/top flags
      if (availableScroll > delta && _this.isBottom) {
        if (onBottomLeave) onBottomLeave(event);
        _this.isBottom = false;
      }
      if (isDeltaPositive && _this.isTop) {
        if (onTopLeave) onTopLeave(event);
        _this.isTop = false;
      }

      // bottom limit
      if (isDeltaPositive && delta > availableScroll) {
        if (onBottomArrive && !_this.isBottom) {
          onBottomArrive(event);
        }
        target.scrollTop = scrollHeight;
        shouldCancelScroll = true;
        _this.isBottom = true;

        // top limit
      } else if (!isDeltaPositive && -delta > scrollTop) {
        if (onTopArrive && !_this.isTop) {
          onTopArrive(event);
        }
        target.scrollTop = 0;
        shouldCancelScroll = true;
        _this.isTop = true;
      }

      // cancel scroll
      if (shouldCancelScroll) {
        _this.cancelScroll(event);
      }
    }, _this.onWheel = function (event) {
      _this.handleEventDelta(event, event.deltaY);
    }, _this.onTouchStart = function (event) {
      // set touch start so we can calculate touchmove delta
      _this.touchStart = event.changedTouches[0].clientY;
    }, _this.onTouchMove = function (event) {
      var deltaY = _this.touchStart - event.changedTouches[0].clientY;
      _this.handleEventDelta(event, deltaY);
    }, _this.getScrollTarget = function (ref) {
      _this.scrollTarget = ref;
    }, _temp), _possibleConstructorReturn(_this, _ret);
  }

  _createClass(ScrollCaptor, [{
    key: 'componentDidMount',
    value: function componentDidMount() {
      this.startListening(this.scrollTarget);
    }
  }, {
    key: 'componentWillUnmount',
    value: function componentWillUnmount() {
      this.stopListening(this.scrollTarget);
    }
  }, {
    key: 'startListening',
    value: function startListening(el) {
      // bail early if no scroll available
      if (el.scrollHeight <= el.clientHeight) return;

      // all the if statements are to appease Flow 😢
      if (typeof el.addEventListener === 'function') {
        el.addEventListener('wheel', this.onWheel, false);
      }
      if (typeof el.addEventListener === 'function') {
        el.addEventListener('touchstart', this.onTouchStart, false);
      }
      if (typeof el.addEventListener === 'function') {
        el.addEventListener('touchmove', this.onTouchMove, false);
      }
    }
  }, {
    key: 'stopListening',
    value: function stopListening(el) {
      // bail early if no scroll available
      if (el.scrollHeight <= el.clientHeight) return;

      // all the if statements are to appease Flow 😢
      if (typeof el.removeEventListener === 'function') {
        el.removeEventListener('wheel', this.onWheel, false);
      }
      if (typeof el.removeEventListener === 'function') {
        el.removeEventListener('touchstart', this.onTouchStart, false);
      }
      if (typeof el.removeEventListener === 'function') {
        el.removeEventListener('touchmove', this.onTouchMove, false);
      }
    }
  }, {
    key: 'render',
    value: function render() {
      return _react2.default.createElement(
        _reactNodeResolver2.default,
        { innerRef: this.getScrollTarget },
        this.props.children
      );
    }
  }]);

  return ScrollCaptor;
}(_react.Component);

exports.default = ScrollCaptor;