custom-listenable/dist/index.js

Create custom listenable with addListener and removeListener methods.

'use strict';

var listenable = function () {
    var listeners = [];
    var findIndex = function (callback) {
        return listeners.findIndex(function (listener) { return listener.callback === callback; });
    };
    var addListener = function (callback, options) {
        if (options === void 0) { options = {}; }
        // Prevent duplicate listeners
        if (findIndex(callback) >= 0) {
            return;
        }
        listeners.push({ callback: callback, options: options });
    };
    var removeListener = function (callback) {
        var listenerIndex = findIndex(callback);
        if (listenerIndex >= 0) {
            listeners.splice(listenerIndex, 1);
        }
    };
    var emit = function (data) {
        listeners.forEach(function (listener) {
            listener.callback(data);
            if (listener.options.once) {
                removeListener(listener.callback);
            }
        });
    };
    return {
        addListener: addListener,
        removeListener: removeListener,
        emit: emit,
    };
};

exports.listenable = listenable;
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