@researchgate/react-intersection-list/lib/js/Sentinel.js

React List Component using the Intersection Observer API

"use strict";

exports.__esModule = true;
exports["default"] = void 0;

var _react = _interopRequireWildcard(require("react"));

var _reactIntersectionObserver = _interopRequireDefault(require("@researchgate/react-intersection-observer"));

var _propTypes = _interopRequireDefault(require("prop-types"));

var _utils = require("./utils");

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

function _getRequireWildcardCache() { if (typeof WeakMap !== "function") return null; var cache = new WeakMap(); _getRequireWildcardCache = function _getRequireWildcardCache() { return cache; }; return cache; }

function _interopRequireWildcard(obj) { if (obj && obj.__esModule) { return obj; } if (obj === null || typeof obj !== "object" && typeof obj !== "function") { return { "default": obj }; } var cache = _getRequireWildcardCache(); if (cache && cache.has(obj)) { return cache.get(obj); } var newObj = {}; var hasPropertyDescriptor = Object.defineProperty && Object.getOwnPropertyDescriptor; for (var key in obj) { if (Object.prototype.hasOwnProperty.call(obj, key)) { var desc = hasPropertyDescriptor ? Object.getOwnPropertyDescriptor(obj, key) : null; if (desc && (desc.get || desc.set)) { Object.defineProperty(newObj, key, desc); } else { newObj[key] = obj[key]; } } } newObj["default"] = obj; if (cache) { cache.set(obj, newObj); } return newObj; }

function _createSuper(Derived) { var hasNativeReflectConstruct = _isNativeReflectConstruct(); return function _createSuperInternal() { var Super = _getPrototypeOf(Derived), result; if (hasNativeReflectConstruct) { var NewTarget = _getPrototypeOf(this).constructor; result = Reflect.construct(Super, arguments, NewTarget); } else { result = Super.apply(this, arguments); } return _possibleConstructorReturn(this, result); }; }

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

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

function _isNativeReflectConstruct() { if (typeof Reflect === "undefined" || !Reflect.construct) return false; if (Reflect.construct.sham) return false; if (typeof Proxy === "function") return true; try { Date.prototype.toString.call(Reflect.construct(Date, [], function () {})); return true; } catch (e) { return false; } }

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

function _inheritsLoose(subClass, superClass) { subClass.prototype = Object.create(superClass.prototype); subClass.prototype.constructor = subClass; subClass.__proto__ = superClass; }

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; }

var Sentinel = /*#__PURE__*/function (_Component) {
  _inheritsLoose(Sentinel, _Component);

  var _super = _createSuper(Sentinel);

  function Sentinel(props) {
    var _this;

    _this = _Component.call(this, props) || this;

    _defineProperty(_assertThisInitialized(_this), "setRootElement", function (rootElement) {
      _this.setState({
        rootElement: rootElement
      });
    });

    _this.state = {
      rootElement: undefined,
      rootMargin: (0, _utils.computeRootMargin)(props)
    };
    _this.target = /*#__PURE__*/_react["default"].createElement("template", {
      style: {
        height: 1,
        minWidth: 1,
        display: 'block'
      }
    });
    props.setRef(_this.setRootElement);
    return _this;
  }

  Sentinel.getDerivedStateFromProps = function getDerivedStateFromProps(_ref, prevState) {
    var threshold = _ref.threshold,
        axis = _ref.axis;
    var newState = null;

    if (threshold !== prevState.threshold || axis !== prevState.axis) {
      newState = {
        threshold: threshold,
        axis: axis,
        rootMargin: (0, _utils.computeRootMargin)({
          threshold: threshold,
          axis: axis
        })
      };
    }

    return newState;
  };

  var _proto = Sentinel.prototype;

  _proto.shouldComponentUpdate = function shouldComponentUpdate(nextProps, _ref2) {
    var rootMargin = _ref2.rootMargin,
        rootElement = _ref2.rootElement;
    var _this$state = this.state,
        currentRootMargin = _this$state.rootMargin,
        currentRootElement = _this$state.rootElement; // When the rootMargin stays the same but the sentinel is repositioned, it can fall within
    // its threshold prematurely. In this case we don't get any update from the Observer instance.
    // We need to guarantee an update, and re-observing is a cheap way to accomplish this.

    if (currentRootMargin === rootMargin && currentRootElement === rootElement) {
      this.observer.externalUnobserve();
      this.observer.observe();
      return false;
    }

    return true;
  };

  _proto.render = function render() {
    var _this2 = this;

    var onChange = this.props.onChange;
    var _this$state2 = this.state,
        rootElement = _this$state2.rootElement,
        rootMargin = _this$state2.rootMargin;
    return /*#__PURE__*/_react["default"].createElement(_reactIntersectionObserver["default"], {
      ref: function ref(instance) {
        _this2.observer = instance;
      },
      disabled: typeof rootElement === 'undefined',
      root: rootElement,
      rootMargin: rootMargin,
      onChange: onChange
    }, this.target);
  };

  return Sentinel;
}(_react.Component);

process.env.NODE_ENV !== "production" ? Sentinel.propTypes = {
  axis: _propTypes["default"].oneOf(['x', 'y']).isRequired,
  threshold: _propTypes["default"].string.isRequired,
  setRef: _propTypes["default"].func.isRequired,
  onChange: _propTypes["default"].func.isRequired
} : void 0;
var _default = Sentinel;
exports["default"] = _default;