@segment/analytics-generic-utils/dist/cjs/emitter/emitter.js

This monorepo's version of "lodash". This package contains shared generic utilities that can be used within the ecosystem. This package should not have dependencies, and should not contain any references to the Analytics domain.

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.Emitter = void 0;
/**
 * Event Emitter that takes the expected contract as a generic
 * @example
 * ```ts
 *  type Contract = {
 *    delivery_success: [DeliverySuccessResponse, Metrics],
 *    delivery_failure: [DeliveryError]
 * }
 *  new Emitter<Contract>()
 *  .on('delivery_success', (res, metrics) => ...)
 *  .on('delivery_failure', (err) => ...)
 * ```
 */
var Emitter = /** @class */ (function () {
    function Emitter(options) {
        var _a;
        this.callbacks = {};
        this.warned = false;
        this.maxListeners = (_a = options === null || options === void 0 ? void 0 : options.maxListeners) !== null && _a !== void 0 ? _a : 10;
    }
    Emitter.prototype.warnIfPossibleMemoryLeak = function (event) {
        if (this.warned) {
            return;
        }
        if (this.maxListeners &&
            this.callbacks[event].length > this.maxListeners) {
            console.warn("Event Emitter: Possible memory leak detected; ".concat(String(event), " has exceeded ").concat(this.maxListeners, " listeners."));
            this.warned = true;
        }
    };
    Emitter.prototype.on = function (event, callback) {
        if (!this.callbacks[event]) {
            this.callbacks[event] = [callback];
        }
        else {
            this.callbacks[event].push(callback);
            this.warnIfPossibleMemoryLeak(event);
        }
        return this;
    };
    Emitter.prototype.once = function (event, callback) {
        var _this = this;
        var on = function () {
            var args = [];
            for (var _i = 0; _i < arguments.length; _i++) {
                args[_i] = arguments[_i];
            }
            _this.off(event, on);
            callback.apply(_this, args);
        };
        this.on(event, on);
        return this;
    };
    Emitter.prototype.off = function (event, callback) {
        var _a;
        var fns = (_a = this.callbacks[event]) !== null && _a !== void 0 ? _a : [];
        var without = fns.filter(function (fn) { return fn !== callback; });
        this.callbacks[event] = without;
        return this;
    };
    Emitter.prototype.emit = function (event) {
        var _this = this;
        var _a;
        var args = [];
        for (var _i = 1; _i < arguments.length; _i++) {
            args[_i - 1] = arguments[_i];
        }
        var callbacks = (_a = this.callbacks[event]) !== null && _a !== void 0 ? _a : [];
        callbacks.forEach(function (callback) {
            callback.apply(_this, args);
        });
        return this;
    };
    return Emitter;
}());
exports.Emitter = Emitter;
//# sourceMappingURL=emitter.js.map