theZieger / utilitiesjs

 * utilities.js | v0.7.0 | Utility functions for front-end JavaScript development

 * Copyright (c) 2017 Eric Zieger (MIT license)

 * https://github.com/theZieger/utilitiesjs/blob/master/LICENSE

 */

    /**

     * inherit the prototype of the SuperConstructor

     * 

     * Warning: Changing the prototype of an object is, by the nature of how modern JavaScript engines

     * optimize property accesses, a very slow operation, in every browser and JavaScript engine.

     * So instead of using Object.setPrototypeOf or messing with __proto__, we create a new object

     * with the desired prototype using Object.create().

     *

     * @see https://developer.mozilla.org/de/docs/Web/JavaScript/Reference/Global_Objects/Object/setPrototypeOf

     *

     * @param {Object} Constructor

     * @param {Object} SuperConstructor

     *

     * @throws {TypeError} if arguments are null/undefined, or SuperConstructor has no prototype

     *

     * @returns {Void}

     */

    var inherits = function(Constructor, SuperConstructor) {

        if (Constructor === undefined || Constructor === null) {

            throw new TypeError('Constructor argument is undefined or null');

        }

        if (SuperConstructor === undefined || SuperConstructor === null) {

            throw new TypeError('SuperConstructor argument is undefined or null');

        }

        if (SuperConstructor.prototype === undefined) {

            throw new TypeError('SuperConstructor.prototype is undefined');

        }

        // for convenience, SuperConstructor will be accessible through the Constructor.super_ property

        Constructor.super_ = SuperConstructor;

        Constructor.prototype = Object.create(SuperConstructor.prototype);

        Constructor.prototype.constructor = Constructor;

    };

    /**

     * Turns Array (of Objects) into associative Object (by given mapBy when given)

     *

     * @param {Array}  arr

     * @param {String} mapBy  optional mapping key

     *

     * @throws {TypeError} if arr is not an Array or mapBy is set but not a String

     *

     * @returns {Object}

     */

    var toObject = function(arr, mapBy) {

        var obj = {};

            throw new TypeError('mapBy argument is not of type String');

        }

        if (!Array.isArray(arr)) {

            throw new TypeError('arr argument is not of type Array');

        }

        arr.forEach(function(val, i) {

            if (!mapBy) {

                obj[i] = val;

            } else if (

                typeof val[mapBy] === 'string'

                || typeof val[mapBy] === 'number'

            ) {

                obj[val[mapBy]] = val;

            }

        });

        return obj;

    };

    return {

        inherits: inherits,

        toObject: toObject

    };

}));