yavent/lib/cjs/index.js

A flexible, lightweight event subscriber & emitter

'use strict';

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

// Standalone events:
// Named events:

/**
 * Create a standalone event.
 * Returns a subscriber function and an emitter function.
 */
function makeEvent() {
  var callbacks = [];
  var callbacksLocked = false; // Clone the callback list if necessary,
  // so the changes will only apply on the next emit.

  function unlockCallbacks() {
    if (callbacksLocked) {
      callbacksLocked = false;
      callbacks = callbacks.slice();
    }
  }

  var on = function on(callback) {
    unlockCallbacks();
    callbacks.push(callback);
    var subscribed = true;
    return function unsubscribe() {
      if (subscribed) {
        subscribed = false;
        unlockCallbacks();
        callbacks.splice(callbacks.indexOf(callback), 1);
      }
    };
  };

  var emit = function emit(payload) {
    callbacksLocked = true;
    var snapshot = callbacks;

    for (var i = 0; i < snapshot.length; ++i) {
      snapshot[i](payload);
    }

    callbacksLocked = false;
  };

  return [on, emit];
}
function makeEvents() {
  var events = {};

  var on = function on(name, callback) {
    var event = events[name];
    if (event == null) event = events[name] = makeEvent();
    return event[0](callback);
  };

  var emit = function emit(name, payload) {
    var event = events[name];
    if (event != null) event[1](payload);
  };

  return [on, emit];
}

exports.makeEvent = makeEvent;
exports.makeEvents = makeEvents;
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