@hypothesis/frontend-shared/lib/util/listener-collection.js

Shared components, styles and utilities for Hypothesis projects

function _defineProperty(e, r, t) { return (r = _toPropertyKey(r)) in e ? Object.defineProperty(e, r, { value: t, enumerable: !0, configurable: !0, writable: !0 }) : e[r] = t, e; }
function _toPropertyKey(t) { var i = _toPrimitive(t, "string"); return "symbol" == typeof i ? i : i + ""; }
function _toPrimitive(t, r) { if ("object" != typeof t || !t) return t; var e = t[Symbol.toPrimitive]; if (void 0 !== e) { var i = e.call(t, r || "default"); if ("object" != typeof i) return i; throw new TypeError("@@toPrimitive must return a primitive value."); } return ("string" === r ? String : Number)(t); }
/**
 * Return the event type that a listener will receive.
 *
 * For example `EventType<HTMLElement, 'keydown'>` evaluates to `KeyboardEvent`.
 *
 * The event type is extracted from the target's `on${Type}` property (eg.
 * `HTMLElement.onkeydown` here) If there is no such property, the type defaults
 * to `Event`.
 */

/**
 * Utility that provides a way to conveniently remove a set of DOM event
 * listeners when they are no longer needed.
 */
export class ListenerCollection {
  constructor() {
    _defineProperty(this, "_listeners", void 0);
    this._listeners = new Map();
  }

  /**
   * Add a listener and return an ID that can be used to remove it later
   */
  add(eventTarget, eventType, listener, options) {
    eventTarget.addEventListener(eventType, listener, options);
    const symbol = Symbol();
    this._listeners.set(symbol, {
      eventTarget,
      eventType,
      listener,
      options
    });
    return symbol;
  }

  /**
   * Remove a specific listener.
   */
  remove(listenerId) {
    const event = this._listeners.get(listenerId);
    if (event) {
      const {
        eventTarget,
        eventType,
        listener,
        options
      } = event;
      eventTarget.removeEventListener(eventType, listener, options);
      this._listeners.delete(listenerId);
    }
  }
  removeAll() {
    this._listeners.forEach(({
      eventTarget,
      eventType,
      listener,
      options
    }) => {
      eventTarget.removeEventListener(eventType, listener, options);
    });
    this._listeners.clear();
  }
}
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