Takes data in a hierarchy and returns a string suitably formatted for a POST request's postBody or a GET request's query component.

querify.js

/**
 * querify
 *
 * Takes data in a hierarchy and returns a string suitably formatted for a POST
 *     request's postBody or a GET request's query component.
 *
 * Note:
 *     This function will not play well with circular referenced objects, it
 *         will result in an infinite loop. Most likely. I haven't tested
 *         that case.
 *
 * @param  {Any}    input           The data you wish to querify
 * @param  {String} keyHierarchy    A key hierarchy to use for subsequent key
 *                                      value pairs. If none is passed, it will
 *                                      be determined automatically based on the
 *                                      input passed. Ex:
 *                                          myKey[0], output: myKey[0][otherKey]
 * @return {String}                 The formatted string. Ex:
 *                                      something=else&nothing=&arrays[0][a]=value&arrays[1]=0
 */
function querify(input, keyHierarchy){
    var hasKeyHierarchy,
        output,
        key,
        currentKey,
        currentItem;

    // This is a bit of a grey area... What to do if the user passes a falsey
    //      or a non object as input?
    if(!input || typeof input !== 'object'){
        if(typeof input === 'object' || typeof input === 'undefined'){
            return '';
        } else {
            return encodeURIComponent(input);
        }
    }

    // determine if there is a key hierarchy
    hasKeyHierarchy = !!(keyHierarchy && typeof keyHierarchy === 'string');
    output = [];

    // we're using for .. in to generically iterate through the object (even if
    //      it is an array), the code becomes simpler this way
    for(key in input){
        // make sure we're not sending any prototype properties
        if(!input.hasOwnProperty(key)){ continue; }

        // let's prepare the current key
        if(hasKeyHierarchy){
            currentKey = keyHierarchy + '[' + encodeURIComponent(key) + ']';
        } else {
            currentKey = encodeURIComponent(key);
        }

        currentItem = input[key];

        // in case of falsey, determine best course of action
        if(!currentItem){
            if(typeof currentItem === 'object' || typeof currentItem === 'undefined'){
                output.push(currentKey + '=');
            } else {
                output.push(currentKey + '=' + encodeURIComponent(currentItem));
            }

            continue;
        }

        // recursively iterate through the object to extract all of the
        // key-value pairs
        if(typeof currentItem === 'object'){
            output.push(querify(currentItem, currentKey));

            continue;
        }

        // add a new key-value pair to the output
        output.push(currentKey + '=' + encodeURIComponent(currentItem));
    }

    // if any property of the original input was an empty object add an empty
    //      entry for it in the output
    if(hasKeyHierarchy && !output.length){
        output.push(keyHierarchy + '=');
    }

    return output.join("&");
}