# Introduction In this challenge, you are tasked with implementing the functionality of a draggable tree-like component for a course scheduling assistant. The goal is to allow users to easily rearrange the course chapters, sections, and experiment documents by dragging and dropping them within the tree structure. You will need to complete the `ajax` function to fetch and save the tree data, the `treeMenusRender` function to generate the DOM structure, and the `treeDataRefresh` function to update the tree data after a drag and drop operation.
Click the virtual machine below to start practicing