Small recursive routine to deeply parse any object and convert all arrays into string lists. Helps when dealing with servers that limit http data parameters.

jsonDeepStringify.js

/**
 * Recurse object and stringify any arrays. This helps when passing paremeters
 * to a server since some servers may limit the number of distinct items in http requests.
 * @param {Object} obj Object to parse
 * @return {Object} Return the parsed object
 */
function jsonDeepStringify(obj) {
    if (Object.prototype.toString.call(obj) == '[object Array]') {
        obj = obj.join(',');
    } else if (typeof (obj) == 'object') {
        for (let i in obj) {
            if (typeof (obj[i]) == 'object') {
                obj[i] = jsonDeepStringify(obj[i]);
            }
        }
    }
    return obj;
}

Edit to better handle cases when the incoming parameter is already an object.