Answer: Use the el-cascader component of Element-UI to implement cascading selection of tree structures. Detailed description: Data structure: A tree structure requires a specific array structure, and each node contains value, label, and children attributes. Performance optimization: a. Lazy loading: only the currently visible nodes are loaded. b. Virtual scrolling: Improve performance of long lists. c. Data preprocessing: convert data formats to optimize rendering. Readability and maintainability: Clear code structure and comments are essential for understanding and maintenance.

Vue and Element-UI cascaded pull-down box tree structure: in-depth analysis and performance optimization

Have you ever been frustrated by the cascaded drop-down box tree structure of Vue and Element-UI? Trust me, you are not alone. This thing looks simple, but it has hidden secrets when applied. If you are not careful, you will fall into the performance pit. In this article, let’s dig through the story behind it, from basic to advanced, and then to performance optimization, to help you master it thoroughly. After reading it, you can not only easily control the tree structure of the cascaded pull-down box, but also avoid many common pitfalls and write efficient and elegant code.

Let’s clarify first: we are discussing using the el-cascader component of Element-UI to implement cascading selection of tree structures. This is not a simple parent-son relationship, but a complex structure that may contain multiple layers of nesting. Understanding this is crucial because it directly determines how we process data and optimize performance.

Element-UI's el-cascader itself provides support for tree structures, the key lies in your data format. It requires a specific array structure, each node contains value , label , and children attributes. value is the unique identifier of the node, label is the displayed text, and children is the array of child nodes. This part is simple, but the reasonable design of the data structure will directly affect subsequent performance. For example, a tree structure with too large depth or a tree structure with too large data volume can cause performance problems. Remember, data is the foundation and data structure is the key.

Let's look at a simple example, assuming your data structure is as follows:

 <code class="javascript">const data = [ { value: '1', label: '一級(jí)菜單1', children: [ { value: '1-1', label: '二級(jí)菜單1-1' }, { value: '1-2', label: '二級(jí)菜單1-2', children: [{ value: '1-2-1', label: '三級(jí)菜單1-2-1' }] } ] }, { value: '2', label: '一級(jí)菜單2', children: [ { value: '2-1', label: '二級(jí)菜單2-1' } ] } ];</code>

Then, in your Vue component, you can use el-cascader like this:

 <code class="vue"><template> <el-cascader v-model="selectedOptions" :options="data" :props="{ checkStrictly: true, value: 'value', label: 'label', children: 'children' }"></el-cascader> </template> <script> export default { data() { return { selectedOptions: [], data: [] //這里需要用上面定義的data賦值}; }, mounted() { this.data = data; } }; </script></code>

This code shows the most basic usage. The checkStrictly property is set to true , indicating that each node can be selected independently instead of having to select the parent node. value , label and children attributes specify the names of the corresponding fields in the data structure.

However, in practical applications, the amount of data is often very large. At this time, performance problems are highlighted. Rendering a large number of nodes can seriously affect page performance. To solve this problem, we can consider the following optimization strategies:

• Lazy loading: Don't load all data at once. Only currently visible nodes are loaded, and their children are loaded when the user expands the node. This requires you to modify the backend interface and support loading data on demand.
• Virtual Scroll: For very long lists, using virtual scrolling technology can significantly improve performance. Element-UI itself does not provide virtual scrolling functionality, you need to use other virtual scrolling libraries, such as vue-virtual-scroller .
• Data preprocessing: After the data is loaded, preprocessing the data, such as converting the data into a format that is more suitable for el-cascader rendering, can reduce rendering time. This requires you to have a deep understanding of the data structure.

Finally, don't forget the readability and maintainability of the code. Clear code structure and comments are not only convenient for one's own understanding and maintenance, but also for teamwork. Remember, elegant code is the key to efficient development. Don't sacrifice the readability of your code in pursuit of so-called "skills". Simple, efficient and maintainable is the kingly way. This is the real way to be a big bull.

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