react-lazily-render/dist/esnext/index.js

Lazily render react components

function _typeof(obj) { if (typeof Symbol === "function" && typeof Symbol.iterator === "symbol") { _typeof = function _typeof(obj) { return typeof obj; }; } else { _typeof = function _typeof(obj) { return obj && typeof Symbol === "function" && obj.constructor === Symbol && obj !== Symbol.prototype ? "symbol" : typeof obj; }; } return _typeof(obj); }

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

function _createClass(Constructor, protoProps, staticProps) { if (protoProps) _defineProperties(Constructor.prototype, protoProps); if (staticProps) _defineProperties(Constructor, staticProps); return Constructor; }

function _possibleConstructorReturn(self, call) { if (call && (_typeof(call) === "object" || typeof call === "function")) { return call; } return _assertThisInitialized(self); }

function _getPrototypeOf(o) { _getPrototypeOf = Object.setPrototypeOf ? Object.getPrototypeOf : function _getPrototypeOf(o) { return o.__proto__ || Object.getPrototypeOf(o); }; return _getPrototypeOf(o); }

function _assertThisInitialized(self) { if (self === void 0) { throw new ReferenceError("this hasn't been initialised - super() hasn't been called"); } return self; }

function _inherits(subClass, superClass) { if (typeof superClass !== "function" && superClass !== null) { throw new TypeError("Super expression must either be null or a function"); } subClass.prototype = Object.create(superClass && superClass.prototype, { constructor: { value: subClass, writable: true, configurable: true } }); if (superClass) _setPrototypeOf(subClass, superClass); }

function _setPrototypeOf(o, p) { _setPrototypeOf = Object.setPrototypeOf || function _setPrototypeOf(o, p) { o.__proto__ = p; return o; }; return _setPrototypeOf(o, p); }

function _defineProperty(obj, key, value) { if (key in obj) { Object.defineProperty(obj, key, { value: value, enumerable: true, configurable: true, writable: true }); } else { obj[key] = value; } return obj; }

import * as React from 'react';
import scrollParent from 'scrollparent';
import _getViewportBounds from './utils/getViewportBounds';
import _getElementBounds from './utils/getElementBounds';
import convertOffsetToBounds from './utils/convertOffsetToBounds';
import isElementInViewport from './utils/isElementInViewport';
import isBackCompatMode from './utils/isBackCompatMode';
import eventListenerOptions from './utils/eventListenerOptions';

var LazilyRender =
/*#__PURE__*/
function (_React$Component) {
  _inherits(LazilyRender, _React$Component);

  function LazilyRender() {
    var _getPrototypeOf2;

    var _this;

    _classCallCheck(this, LazilyRender);

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

    _this = _possibleConstructorReturn(this, (_getPrototypeOf2 = _getPrototypeOf(LazilyRender)).call.apply(_getPrototypeOf2, [this].concat(args)));

    _defineProperty(_assertThisInitialized(_this), "raf", void 0);

    _defineProperty(_assertThisInitialized(_this), "element", void 0);

    _defineProperty(_assertThisInitialized(_this), "container", void 0);

    _defineProperty(_assertThisInitialized(_this), "state", {
      hasBeenScrolledIntoView: false
    });

    _defineProperty(_assertThisInitialized(_this), "update", function () {
      cancelAnimationFrame(_this.raf);
      _this.raf = requestAnimationFrame(function () {
        var elementBounds = _this.getElementBounds();

        var viewportBounds = _this.getViewportBounds();

        var offsetBounds = _this.getOffsetBounds();

        if (!elementBounds || !viewportBounds) {
          return;
        }

        if (isElementInViewport(elementBounds, viewportBounds, offsetBounds)) {
          _this.stopListening(_this.container);

          _this.setState({
            hasBeenScrolledIntoView: true
          }, function () {
            var onRender = _this.props.onRender;

            if (onRender) {
              onRender();
            }
          });
        }
      });
    });

    _defineProperty(_assertThisInitialized(_this), "handleMount", function (element) {
      var scrollContainer = _this.props.scrollContainer;
      _this.element = element;
      _this.container = _this.getContainer(scrollContainer);
    });

    return _this;
  }

  _createClass(LazilyRender, [{
    key: "getContainer",
    value: function getContainer(scrollContainer) {
      if (scrollContainer) {
        return scrollContainer;
      } else {
        if (this.element) {
          var container = scrollParent(this.element);

          if (container === document.scrollingElement || container === document.documentElement || !isBackCompatMode() && container == document.body) {
            return window;
          } else {
            return container;
          }
        } else {
          return undefined;
        }
      }
    }
  }, {
    key: "getViewportBounds",
    value: function getViewportBounds() {
      return _getViewportBounds(this.container);
    }
  }, {
    key: "getElementBounds",
    value: function getElementBounds() {
      return _getElementBounds(this.element);
    }
  }, {
    key: "getOffsetBounds",
    value: function getOffsetBounds() {
      var offset = this.props.offset;
      return convertOffsetToBounds(offset);
    }
  }, {
    key: "componentDidUpdate",
    value: function componentDidUpdate(prevProps, prevState) {
      var _this2 = this;

      var prevContainer = prevProps.scrollContainer;
      var nextContainer = this.props.scrollContainer; // If a scroll container was defined before, do some cleanup
      // and bootstrap the next scroll container.

      if (prevContainer !== nextContainer) {
        // If the previous container was already utilised, no cleanup
        // is required - already done in LazilyRender.update().
        if (!prevState.hasBeenScrolledIntoView) {
          this.stopListening(prevContainer);
        } // Set a new listener if the scrollContainer is defined, and update 
        // the container property accordingly. Note: this should only be done
        // when the next container is different.


        this.container = this.getContainer(nextContainer);
        this.startListening(this.container); // Signal that the element has not been scrolled into view and 
        // recompute its position. This will essentially 'reset' the node's
        // current status back to a placeholder item if need be.

        this.setState({
          hasBeenScrolledIntoView: false
        }, function () {
          _this2.update();
        });
      }
    }
  }, {
    key: "startListening",
    value: function startListening(container) {
      if (container) container.addEventListener('scroll', this.update, eventListenerOptions);
      window.addEventListener('resize', this.update);
    }
  }, {
    key: "stopListening",
    value: function stopListening(container) {
      if (container) container.removeEventListener('scroll', this.update, eventListenerOptions);
      window.removeEventListener('resize', this.update);
    }
  }, {
    key: "componentDidMount",
    value: function componentDidMount() {
      this.update();
      this.startListening(this.container);
    }
  }, {
    key: "componentWillUnmount",
    value: function componentWillUnmount() {
      this.stopListening(this.container);
    }
  }, {
    key: "renderChildren",
    value: function renderChildren() {
      var _this$props = this.props,
          placeholder = _this$props.placeholder,
          content = _this$props.content,
          children = _this$props.children;
      var hasBeenScrolledIntoView = this.state.hasBeenScrolledIntoView;

      if (!hasBeenScrolledIntoView && placeholder) {
        return placeholder;
      }

      if (hasBeenScrolledIntoView && content) {
        return content;
      }

      if (children) {
        return children(hasBeenScrolledIntoView);
      }

      return null;
    }
  }, {
    key: "render",
    value: function render() {
      var _this$props2 = this.props,
          className = _this$props2.className,
          component = _this$props2.component;
      return React.createElement(component || 'div', {
        ref: this.handleMount,
        className: className,
        children: this.renderChildren()
      });
    }
  }]);

  return LazilyRender;
}(React.Component);

export { LazilyRender as default };