Append an existing JavaScript callback

callback-append.js

/**
 * Append an existing callback.
 * @param {function} callback Callback to append.
 * @param {function} append Data appended to the existing callback.
 * @returns {function} Returns the newly assembled callback.
 */
function appendCallback(callback, append) {
    var newCallback = function () {
        callback();
        append();
    };
            
    return newCallback;
}