instantiate.js

// JSON is a peer dependency so will be loaded

if (typeof JSON.instantiate !== 'function') {

    /*

        JSON Schema Instantiator
        
        https://github.com/tomarad/JSON-Schema-Instantiator
        
        The MIT License (MIT)

        Copyright (c) 2015 Tom Arad

        Permission is hereby granted, free of charge, to any person obtaining a copy of this software 
        and associated documentation files (the "Software"), to deal in the Software without restriction,
        including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, 
        and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, 
        subject to the following conditions:

        The above copyright notice and this permission notice shall be included in all copies 
        or substantial portions of the Software.

        THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, 
        INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR 
        PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE 
        FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, 
        ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

    */

    JSON.instantiate = function(schema, options) {
        'use strict';

        options = options || {};

        // Set requiredPropertiesOnly to true if not defined
        if ( typeof options.requiredPropertiesOnly === 'undefined') options.requiredPropertiesOnly = true;

        // The JSON Object that defines the default values of certain types.
        var typesInstantiator = {
            'string': '',
            'number': 0,
            'integer': 0,
            'null': null,
            'boolean': false, // Always stay positive?
            'object': { }
        };

        /**
         * Checks whether a variable is a primitive.
         * @param obj - an object.
         * @returns {boolean}
         */
        function isPrimitive(obj) {
            var type = obj.type;

            return typesInstantiator[type] !== undefined;
        };

        /**
         * Checks whether a property is on required array.
         * @param property - the property to check.
         * @param requiredArray - the required array
         * @returns {boolean}
         */
        function isPropertyRequired(property, requiredArray) {
            var found = false;
            requiredArray = requiredArray || [];
            requiredArray.forEach(function(requiredProperty) {
                    if (requiredProperty === property) {
                        found = true;
                    };
            });
            return found;
        };


        function shouldVisit(property, obj, options) {
                return (!options.requiredPropertiesOnly) || (options.requiredPropertiesOnly && isPropertyRequired(property, obj.required));
        };

        /**
         * Instantiate a primitive.
         * @param val - The object that represents the primitive.
         * @returns {*}
         */
        function instantiatePrimitive(val) {
            var type = val.type;

            // Support for default values in the JSON Schema.
            if (val.default) {
                return val.default;
            };

            return typesInstantiator[type];
        };

        /**
         * Checks whether a variable is an enum.
         * @param obj - an object.
         * @returns {boolean}
         */
        function isEnum(obj) {
            return Object.prototype.toString.call(obj.enum) === '[object Array]';
        };

        /**
         * Extracts the type of the object.
         * If the type is an array, set type to first in list of types.
         * If obj.type is not overridden, it will fail the isPrimitive check.
         * Which internally also checks obj.type.
         * @param obj - An object.
        */
        function getObjectType(obj) {
            // Check if type is array of types.
            if (Array.isArray(obj.type)) {
                obj.type = obj.type[0];
            };

            return obj.type;
        };

        /**
         * Instantiate an enum.
         * @param val - The object that represents the primitive.
         * @returns {*}
         */
        function instantiateEnum(val) {
            // Support for default values in the JSON Schema.
            if (val.default) {
                    return val.default;
            };
            if (!val.enum.length) {
                    return undefined;
            };
            return val.enum[0];
        };

        /**
         * Visits each sub-object using recursion.
         * If it reaches a primitive, instantiate it.
         * @param obj - The object that represents the schema.
         * @param name - The name of the current object.
         * @param data - The instance data that represents the current object.
         */
        function visit(obj, name, data) {
            if (!obj) {
                return;
            };

            var i;
            var type = getObjectType(obj);

            // We want non-primitives objects (primitive === object w/o properties).
            if (type === 'object' && obj.properties) {
                data[name] = data[name] || { };

                // Visit each property.
                for (var property in obj.properties) {
                    if (obj.properties.hasOwnProperty(property)) {
                        if (shouldVisit(property, obj, options)) {
                            visit(obj.properties[property], property, data[name]);
                        };
                    };
                };
            } else if (obj.allOf) {
                for (i = 0; i < obj.allOf.length; i++) {
                    visit(obj.allOf[i], name, data);
                };
            } else if (type === 'array') {
                data[name] = [];
                var len = 0;
                if (obj.minItems || obj.minItems > 0) {
                    len = obj.minItems;
                };

                // Instantiate 'len' items.
                for (i = 0; i < len; i++) {
                    visit(obj.items, i, data[name]);
                };
            } else if (isEnum(obj)) {
                data[name] = instantiateEnum(obj);
            } else if (isPrimitive(obj)) {
                data[name] = instantiatePrimitive(obj);
            };
        };

        var data = {};
        visit(schema, 'kek', data);
        return data['kek'];
    };

};