如何使用jquery每个函数从每个li获取数据？

I have a unordered list and each list element have "data-id" attribute, the idea is that using JQuery's each function iterate through each list element and get the "data-id" value and dynamically assign the position, ie to make a item slider that slides one item at a time. but on each the value of data I'm getting is I have a unordered list and each list element h