Combine user attributes with known attributes and fill in defaults when needed.

shortcode-params.js

/* exported shortcodeParams */

/**
 * Combine user attributes with known attributes and fill in defaults when needed.
 *
 * The defaults should be considered to be all of the attributes which are
 * supported by the caller and given as a list. The returned attributes will
 * only contain the attributes in the defaults list.
 *
 * If the params list has unsupported attributes, then they will be ignored and
 * removed from the final returned list.
 *
 *
 * @param array defaults Entire list of supported attributes and their defaults.
 * @param array params User defined attributes in shortcode tag.
 * @return array Combined and filtered attribute list.
 */
var shortcodeParams = function (defaults, params) {
  
	'use strict';

	if (typeof params !== 'object') { return defaults; }

	var out = {};
	
	for (var key in defaults) {
		if (defaults.hasOwnProperty(key)) {
			if (params[key]) {
				out[key] = params[key];
			} else {
				out[key] = defaults[key];
			}
		}
	}

	return out;
};