js/utils/common.js
function mergeAsArray(destination, source, property) {
    destination[property] = source[property].concat(destination[property] || []);
}
function mergeAsArray(destination, source, property) {
    destination[property] = source[property].concat(destination[property] || []);
}
Merges arrays by concatenating them

@param {Object} destination
@param {Object} source
@param {String} property