javascript定时执行方法

function aa () {
var common;
onclickLI("xueya", 1, 10);  //页面以打开时第一次执行
common = setInterval("onclickLI('xueya'," + 1 + "," + 10 + ");", 30000);
$(".th").click(function () {  //click事件发生时执行
if (common) {
window.clearInterval(common);
}
common = setInterval("onclickLI('" + $(this).attr("id") + "'," + 1 + "," + 10 + ");", 30000);
});

}