react-lazyload/lib/index.js

Lazyload your components, images or anything where performance matters.

'use strict';

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.forceVisible = exports.forceCheck = exports.lazyload = undefined;

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 _propTypes = require('prop-types');

var _propTypes2 = _interopRequireDefault(_propTypes);

var _event = require('./utils/event');

var _scrollParent = require('./utils/scrollParent');

var _scrollParent2 = _interopRequireDefault(_scrollParent);

var _debounce = require('./utils/debounce');

var _debounce2 = _interopRequireDefault(_debounce);

var _throttle = require('./utils/throttle');

var _throttle2 = _interopRequireDefault(_throttle);

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; } /**
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                * react-lazyload
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                */


var defaultBoundingClientRect = {
  top: 0,
  right: 0,
  bottom: 0,
  left: 0,
  width: 0,
  height: 0
};
var LISTEN_FLAG = 'data-lazyload-listened';
var listeners = [];
var pending = [];

// try to handle passive events
var passiveEventSupported = false;
try {
  var opts = Object.defineProperty({}, 'passive', {
    get: function get() {
      passiveEventSupported = true;
    }
  });
  window.addEventListener('test', null, opts);
} catch (e) {}
// if they are supported, setup the optional params
// IMPORTANT: FALSE doubles as the default CAPTURE value!
var passiveEvent = passiveEventSupported ? { capture: false, passive: true } : false;

/**
 * Check if `component` is visible in overflow container `parent`
 * @param  {node} component React component
 * @param  {node} parent    component's scroll parent
 * @return {bool}
 */
var checkOverflowVisible = function checkOverflowVisible(component, parent) {
  var node = component.ref;

  var parentTop = void 0;
  var parentLeft = void 0;
  var parentHeight = void 0;
  var parentWidth = void 0;

  try {
    var _parent$getBoundingCl = parent.getBoundingClientRect();

    parentTop = _parent$getBoundingCl.top;
    parentLeft = _parent$getBoundingCl.left;
    parentHeight = _parent$getBoundingCl.height;
    parentWidth = _parent$getBoundingCl.width;
  } catch (e) {
    parentTop = defaultBoundingClientRect.top;
    parentLeft = defaultBoundingClientRect.left;
    parentHeight = defaultBoundingClientRect.height;
    parentWidth = defaultBoundingClientRect.width;
  }

  var windowInnerHeight = window.innerHeight || document.documentElement.clientHeight;
  var windowInnerWidth = window.innerWidth || document.documentElement.clientWidth;

  // calculate top and height of the intersection of the element's scrollParent and viewport
  var intersectionTop = Math.max(parentTop, 0); // intersection's top relative to viewport
  var intersectionLeft = Math.max(parentLeft, 0); // intersection's left relative to viewport
  var intersectionHeight = Math.min(windowInnerHeight, parentTop + parentHeight) - intersectionTop; // height
  var intersectionWidth = Math.min(windowInnerWidth, parentLeft + parentWidth) - intersectionLeft; // width

  // check whether the element is visible in the intersection
  var top = void 0;
  var left = void 0;
  var height = void 0;
  var width = void 0;

  try {
    var _node$getBoundingClie = node.getBoundingClientRect();

    top = _node$getBoundingClie.top;
    left = _node$getBoundingClie.left;
    height = _node$getBoundingClie.height;
    width = _node$getBoundingClie.width;
  } catch (e) {
    top = defaultBoundingClientRect.top;
    left = defaultBoundingClientRect.left;
    height = defaultBoundingClientRect.height;
    width = defaultBoundingClientRect.width;
  }

  var offsetTop = top - intersectionTop; // element's top relative to intersection
  var offsetLeft = left - intersectionLeft; // element's left relative to intersection

  var offsets = Array.isArray(component.props.offset) ? component.props.offset : [component.props.offset, component.props.offset]; // Be compatible with previous API

  return offsetTop - offsets[0] <= intersectionHeight && offsetTop + height + offsets[1] >= 0 && offsetLeft - offsets[0] <= intersectionWidth && offsetLeft + width + offsets[1] >= 0;
};

/**
 * Check if `component` is visible in document
 * @param  {node} component React component
 * @return {bool}
 */
var checkNormalVisible = function checkNormalVisible(component) {
  var node = component.ref;

  // If this element is hidden by css rules somehow, it's definitely invisible
  if (!(node.offsetWidth || node.offsetHeight || node.getClientRects().length)) return false;

  var top = void 0;
  var elementHeight = void 0;

  try {
    var _node$getBoundingClie2 = node.getBoundingClientRect();

    top = _node$getBoundingClie2.top;
    elementHeight = _node$getBoundingClie2.height;
  } catch (e) {
    top = defaultBoundingClientRect.top;
    elementHeight = defaultBoundingClientRect.height;
  }

  var windowInnerHeight = window.innerHeight || document.documentElement.clientHeight;

  var offsets = Array.isArray(component.props.offset) ? component.props.offset : [component.props.offset, component.props.offset]; // Be compatible with previous API

  return top - offsets[0] <= windowInnerHeight && top + elementHeight + offsets[1] >= 0;
};

/**
 * Detect if element is visible in viewport, if so, set `visible` state to true.
 * If `once` prop is provided true, remove component as listener after checkVisible
 *
 * @param  {React} component   React component that respond to scroll and resize
 */
var checkVisible = function checkVisible(component) {
  var node = component.ref;
  if (!(node instanceof HTMLElement)) {
    return;
  }

  var parent = (0, _scrollParent2.default)(node);
  var isOverflow = component.props.overflow && parent !== node.ownerDocument && parent !== document && parent !== document.documentElement;
  var visible = isOverflow ? checkOverflowVisible(component, parent) : checkNormalVisible(component);
  if (visible) {
    // Avoid extra render if previously is visible
    if (!component.visible) {
      if (component.props.once) {
        pending.push(component);
      }

      component.visible = true;
      component.forceUpdate();
    }
  } else if (!(component.props.once && component.visible)) {
    component.visible = false;
    if (component.props.unmountIfInvisible) {
      component.forceUpdate();
    }
  }
};

var purgePending = function purgePending() {
  pending.forEach(function (component) {
    var index = listeners.indexOf(component);
    if (index !== -1) {
      listeners.splice(index, 1);
    }
  });

  pending = [];
};

var lazyLoadHandler = function lazyLoadHandler() {
  for (var i = 0; i < listeners.length; ++i) {
    var listener = listeners[i];
    checkVisible(listener);
  }
  // Remove `once` component in listeners
  purgePending();
};

/**
 * Forces the component to display regardless of whether the element is visible in the viewport.
 */
var forceVisible = function forceVisible() {
  for (var i = 0; i < listeners.length; ++i) {
    var listener = listeners[i];
    listener.visible = true;
    listener.forceUpdate();
  }
  // Remove `once` component in listeners
  purgePending();
};

// Depending on component's props
var delayType = void 0;
var finalLazyLoadHandler = null;

var isString = function isString(string) {
  return typeof string === 'string';
};

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

  function LazyLoad(props) {
    _classCallCheck(this, LazyLoad);

    var _this = _possibleConstructorReturn(this, (LazyLoad.__proto__ || Object.getPrototypeOf(LazyLoad)).call(this, props));

    _this.visible = false;
    _this.setRef = _this.setRef.bind(_this);
    return _this;
  }

  _createClass(LazyLoad, [{
    key: 'componentDidMount',
    value: function componentDidMount() {
      // It's unlikely to change delay type on the fly, this is mainly
      // designed for tests
      var scrollport = window;
      var scrollContainer = this.props.scrollContainer;

      if (scrollContainer) {
        if (isString(scrollContainer)) {
          scrollport = scrollport.document.querySelector(scrollContainer);
        }
      }
      var needResetFinalLazyLoadHandler = this.props.debounce !== undefined && delayType === 'throttle' || delayType === 'debounce' && this.props.debounce === undefined;

      if (needResetFinalLazyLoadHandler) {
        (0, _event.off)(scrollport, 'scroll', finalLazyLoadHandler, passiveEvent);
        (0, _event.off)(window, 'resize', finalLazyLoadHandler, passiveEvent);
        finalLazyLoadHandler = null;
      }

      if (!finalLazyLoadHandler) {
        if (this.props.debounce !== undefined) {
          finalLazyLoadHandler = (0, _debounce2.default)(lazyLoadHandler, typeof this.props.debounce === 'number' ? this.props.debounce : 300);
          delayType = 'debounce';
        } else if (this.props.throttle !== undefined) {
          finalLazyLoadHandler = (0, _throttle2.default)(lazyLoadHandler, typeof this.props.throttle === 'number' ? this.props.throttle : 300);
          delayType = 'throttle';
        } else {
          finalLazyLoadHandler = lazyLoadHandler;
        }
      }

      if (this.props.overflow) {
        var parent = (0, _scrollParent2.default)(this.ref);
        if (parent && typeof parent.getAttribute === 'function') {
          var listenerCount = 1 + +parent.getAttribute(LISTEN_FLAG);
          if (listenerCount === 1) {
            parent.addEventListener('scroll', finalLazyLoadHandler, passiveEvent);
          }
          parent.setAttribute(LISTEN_FLAG, listenerCount);
        }
      } else if (listeners.length === 0 || needResetFinalLazyLoadHandler) {
        var _props = this.props,
            scroll = _props.scroll,
            resize = _props.resize;


        if (scroll) {
          (0, _event.on)(scrollport, 'scroll', finalLazyLoadHandler, passiveEvent);
        }

        if (resize) {
          (0, _event.on)(window, 'resize', finalLazyLoadHandler, passiveEvent);
        }
      }

      listeners.push(this);
      checkVisible(this);
    }
  }, {
    key: 'shouldComponentUpdate',
    value: function shouldComponentUpdate() {
      return this.visible;
    }
  }, {
    key: 'componentWillUnmount',
    value: function componentWillUnmount() {
      if (this.props.overflow) {
        var parent = (0, _scrollParent2.default)(this.ref);
        if (parent && typeof parent.getAttribute === 'function') {
          var listenerCount = +parent.getAttribute(LISTEN_FLAG) - 1;
          if (listenerCount === 0) {
            parent.removeEventListener('scroll', finalLazyLoadHandler, passiveEvent);
            parent.removeAttribute(LISTEN_FLAG);
          } else {
            parent.setAttribute(LISTEN_FLAG, listenerCount);
          }
        }
      }

      var index = listeners.indexOf(this);
      if (index !== -1) {
        listeners.splice(index, 1);
      }

      if (listeners.length === 0 && typeof window !== 'undefined') {
        (0, _event.off)(window, 'resize', finalLazyLoadHandler, passiveEvent);
        (0, _event.off)(window, 'scroll', finalLazyLoadHandler, passiveEvent);
      }
    }
  }, {
    key: 'setRef',
    value: function setRef(element) {
      if (element) {
        this.ref = element;
      }
    }
  }, {
    key: 'render',
    value: function render() {
      var _props2 = this.props,
          height = _props2.height,
          children = _props2.children,
          placeholder = _props2.placeholder,
          className = _props2.className,
          classNamePrefix = _props2.classNamePrefix,
          style = _props2.style;


      return _react2.default.createElement(
        'div',
        { className: classNamePrefix + '-wrapper ' + className, ref: this.setRef, style: style },
        this.visible ? children : placeholder ? placeholder : _react2.default.createElement('div', {
          style: { height: height },
          className: classNamePrefix + '-placeholder'
        })
      );
    }
  }]);

  return LazyLoad;
}(_react.Component);

LazyLoad.propTypes = {
  className: _propTypes2.default.string,
  classNamePrefix: _propTypes2.default.string,
  once: _propTypes2.default.bool,
  height: _propTypes2.default.oneOfType([_propTypes2.default.number, _propTypes2.default.string]),
  offset: _propTypes2.default.oneOfType([_propTypes2.default.number, _propTypes2.default.arrayOf(_propTypes2.default.number)]),
  overflow: _propTypes2.default.bool,
  resize: _propTypes2.default.bool,
  scroll: _propTypes2.default.bool,
  children: _propTypes2.default.node,
  throttle: _propTypes2.default.oneOfType([_propTypes2.default.number, _propTypes2.default.bool]),
  debounce: _propTypes2.default.oneOfType([_propTypes2.default.number, _propTypes2.default.bool]),
  placeholder: _propTypes2.default.node,
  scrollContainer: _propTypes2.default.oneOfType([_propTypes2.default.string, _propTypes2.default.object]),
  unmountIfInvisible: _propTypes2.default.bool,
  style: _propTypes2.default.object
};

LazyLoad.defaultProps = {
  className: '',
  classNamePrefix: 'lazyload',
  once: false,
  offset: 0,
  overflow: false,
  resize: false,
  scroll: true,
  unmountIfInvisible: false
};

var getDisplayName = function getDisplayName(WrappedComponent) {
  return WrappedComponent.displayName || WrappedComponent.name || 'Component';
};

var decorator = function decorator() {
  var options = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : {};
  return function lazyload(WrappedComponent) {
    return function (_Component2) {
      _inherits(LazyLoadDecorated, _Component2);

      function LazyLoadDecorated() {
        _classCallCheck(this, LazyLoadDecorated);

        var _this2 = _possibleConstructorReturn(this, (LazyLoadDecorated.__proto__ || Object.getPrototypeOf(LazyLoadDecorated)).call(this));

        _this2.displayName = 'LazyLoad' + getDisplayName(WrappedComponent);
        return _this2;
      }

      _createClass(LazyLoadDecorated, [{
        key: 'render',
        value: function render() {
          return _react2.default.createElement(
            LazyLoad,
            options,
            _react2.default.createElement(WrappedComponent, this.props)
          );
        }
      }]);

      return LazyLoadDecorated;
    }(_react.Component);
  };
};

exports.lazyload = decorator;
exports.default = LazyLoad;
exports.forceCheck = lazyLoadHandler;
exports.forceVisible = forceVisible;