try like this
function callAction(btn) {
var button = btn.innerText;
if (button == 'Next') {
}
}
this.buttons = {
next: $('<a onclick="callAction(this)" >' + options.labelNext + '</a>').attr("href", "#").addClass("buttonNext"),
previous: $('<a onclick="callAction(this)" >' + options.labelPrevious + '</a>').attr("href", "#").addClass("buttonPrevious"),
finish: $('<a onclick="callAction(this)" >' + options.labelFinish + '</a>').attr("href", "#").addClass("buttonFinish")
};