How to build a recursive component into a tree menu in Vue.js
This time I will show you how Vue.js builds recursive components into tree menus. What are the precautions for Vue.js to build recursive components into tree menus? The following are Let’s take a look at practical cases.
In Vue.js, a recursive component calls itself, such as:
Vue.component('recursive-component', {
template: `<!--Invoking myself!-->
<recursive-component></recursive-component>
});Recursive components are often used to display comments on blogs, nested menus, or basically the same type as parent and child, although the specific content is different.
Now to show you how to use recursive components effectively, I will proceed step by step by building an expandable/collapse tree menu.
data structure
A recursive component of a tree UI would be a visual representation of some recursive data structure. In this tutorial we will use a tree structure where each node is an object:
A label attribute.
If it has child nodes, a nodes property is an array property of one or more nodes.
Like all tree structures, it must have a root node, but can be infinitely deep.
let tree = {
label: 'root',
nodes: [
{
label: 'item1',
nodes: [
{
label: 'item1.1'
},
{
label: 'item1.2',
nodes: [
{
label: 'item1.2.1'
}
]
}
]
},
{
label: 'item2'
}
]
}Recursive components
Let's make a recursive component to display our data structure called TreeMenu. It only displays the current node's label, and calls itself to display any child nodes. File name: TreeMenu.vue, content is as follows:
<template>
<p class="tree-menu">
<p>{{ label }}</p>
<tree-menu
v-for="node in nodes"
:nodes="node.nodes"
:label="node.label"
>
</tree-menu>
</p>
</template>
<script>
export default {
props: [ 'label', 'nodes' ],
name: 'tree-menu'
}
</script>If you use a component recursively, you must first give Vue.component a global definition, or give it a name attribute. Otherwise, any child component will not be able to call it further and you will get an undefined "undefined component error" error message.
Basic events
As with any recursive function, you need a base event to end the recursion, otherwise rendering will continue indefinitely, eventually causing a stack overflow.
In the tree menu, we want to stop the recursion when we reach a node that has no children. You can do this with v-if, but we choose to use v-for This will be implemented for us implicitly; if the nodes array doesn't have any further definition the tree-menu component will be called. The template.vue file is as follows:
<template> <p class="tree-menu"> ... <!--If `nodes` is undefined this will not render--> <tree-menu v-for="node in nodes"></tree-menu> </template>
Usage
How do we use this component now? First, we declare a Vue instance with a data structure including the data attribute and the defined treemenu component. The app.js file is as follows:
import TreeMenu from './TreeMenu.vue'
let tree = {
...
}
new Vue({
el: '#app',
data: {
tree
},
components: {
TreeMenu
}
})Remember, our data structure has a root node. We start calling the TreeMenu component recursively from the main template, using the root nodes attribute to props:
<p id="app"> <tree-menu :label="tree.label" :nodes="tree.nodes"></tree-menu> </p>
It's good to visually identify the "depth" of subcomponents so users can get a feel for the data structure from the UI. Let's achieve this by indenting the child nodes at each level.
This is achieved by adding a depth prop definition through TreeMenu. We will use this value to dynamically bind inline styles with transforms: we will use the transform: translate CSS rule for each node's label, thus creating an indent. template.vue is modified as follows**:**
<template>
<p class="tree-menu">
<p :style="indent">{{ label }}</p>
<tree-menu
v-for="node in nodes"
:nodes="node.nodes"
:label="node.label"
:depth="depth + 1"
>
</tree-menu>
</p>
</template>
<script>
export default {
props: [ 'label', 'nodes', 'depth' ],
name: 'tree-menu',
computed: {
indent() {
return { transform: `translate(${this.depth * 50}px)` }
}
}
}
</script>The depth attribute starts from zero in the main template. In the component template above, you can see that this value is incremented every time it is passed to any child node.
<p id="app"> <tree-menu :label="tree.label" :nodes="tree.nodes" :depth="0" ></tree-menu> </p>
Note: Remember to v-bind the depth value to ensure it is a JavaScript number type and not a string.
Expand/Collapse
Because recursive data structures can be large, a good UI trick for displaying them is to hide all nodes except the root node so that the user can expand or collapse the nodes as needed.
To do this, we will add a local property showChildren. If its value is False, the child node will not be rendered. This value should be toggled by clicking on the node, so we need to use a click event listener method toggleChildren to manage it. The template.vue file is modified as follows**:**
<template>
<p class="tree-menu">
<p :style="indent" @click="toggleChildren">{{ label }}</p>
<tree-menu
v-if="showChildren"
v-for="node in nodes"
:nodes="node.nodes"
:label="node.label"
:depth="depth + 1"
>
</tree-menu>
</p>
</template>
<script>
export default {
props: [ 'label', 'nodes', 'depth' ],
data() {
return { showChildren: false }
},
name: 'tree-menu',
computed: {
indent() {
return { transform: `translate(${this.depth * 50}px)` }
}
},
methods: {
toggleChildren() {
this.showChildren = !this.showChildren;
}
}
}
</script>Summarize
This way, we have a working tree menu. As a finishing touch, you can add a plus/minus icon to make the UI more visible. I also added very good fonts and computing performance based on the original showChildren
I believe you have mastered the method after reading the case in this article. For more exciting information, please pay attention to other related articles on the PHP Chinese website!
Recommended reading:
How to use VueRouter’s navigation guard
The above is the detailed content of How to build a recursive component into a tree menu in Vue.js. For more information, please follow other related articles on the PHP Chinese website!
Hot AI Tools
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Undress AI Tool
Undress images for free
Clothoff.io
AI clothes remover
Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!
Hot Article
Hot Tools
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
Hot Topics
How to implement an online speech recognition system using WebSocket and JavaScript
Dec 17, 2023 pm 02:54 PM
How to use WebSocket and JavaScript to implement an online speech recognition system Introduction: With the continuous development of technology, speech recognition technology has become an important part of the field of artificial intelligence. The online speech recognition system based on WebSocket and JavaScript has the characteristics of low latency, real-time and cross-platform, and has become a widely used solution. This article will introduce how to use WebSocket and JavaScript to implement an online speech recognition system.
WebSocket and JavaScript: key technologies for implementing real-time monitoring systems
Dec 17, 2023 pm 05:30 PM
WebSocket and JavaScript: Key technologies for realizing real-time monitoring systems Introduction: With the rapid development of Internet technology, real-time monitoring systems have been widely used in various fields. One of the key technologies to achieve real-time monitoring is the combination of WebSocket and JavaScript. This article will introduce the application of WebSocket and JavaScript in real-time monitoring systems, give code examples, and explain their implementation principles in detail. 1. WebSocket technology
How to use JavaScript and WebSocket to implement a real-time online ordering system
Dec 17, 2023 pm 12:09 PM
Introduction to how to use JavaScript and WebSocket to implement a real-time online ordering system: With the popularity of the Internet and the advancement of technology, more and more restaurants have begun to provide online ordering services. In order to implement a real-time online ordering system, we can use JavaScript and WebSocket technology. WebSocket is a full-duplex communication protocol based on the TCP protocol, which can realize real-time two-way communication between the client and the server. In the real-time online ordering system, when the user selects dishes and places an order
JavaScript and WebSocket: Building an efficient real-time weather forecasting system
Dec 17, 2023 pm 05:13 PM
JavaScript and WebSocket: Building an efficient real-time weather forecast system Introduction: Today, the accuracy of weather forecasts is of great significance to daily life and decision-making. As technology develops, we can provide more accurate and reliable weather forecasts by obtaining weather data in real time. In this article, we will learn how to use JavaScript and WebSocket technology to build an efficient real-time weather forecast system. This article will demonstrate the implementation process through specific code examples. We
Simple JavaScript Tutorial: How to Get HTTP Status Code
Jan 05, 2024 pm 06:08 PM
JavaScript tutorial: How to get HTTP status code, specific code examples are required. Preface: In web development, data interaction with the server is often involved. When communicating with the server, we often need to obtain the returned HTTP status code to determine whether the operation is successful, and perform corresponding processing based on different status codes. This article will teach you how to use JavaScript to obtain HTTP status codes and provide some practical code examples. Using XMLHttpRequest
Smooth build: How to correctly configure the Maven image address
Feb 20, 2024 pm 08:48 PM
Smooth build: How to correctly configure the Maven image address When using Maven to build a project, it is very important to configure the correct image address. Properly configuring the mirror address can speed up project construction and avoid problems such as network delays. This article will introduce how to correctly configure the Maven mirror address and give specific code examples. Why do you need to configure the Maven image address? Maven is a project management tool that can automatically build projects, manage dependencies, generate reports, etc. When building a project in Maven, usually
How to get HTTP status code in JavaScript the easy way
Jan 05, 2024 pm 01:37 PM
Introduction to the method of obtaining HTTP status code in JavaScript: In front-end development, we often need to deal with the interaction with the back-end interface, and HTTP status code is a very important part of it. Understanding and obtaining HTTP status codes helps us better handle the data returned by the interface. This article will introduce how to use JavaScript to obtain HTTP status codes and provide specific code examples. 1. What is HTTP status code? HTTP status code means that when the browser initiates a request to the server, the service
Optimize the Maven project packaging process and improve development efficiency
Feb 24, 2024 pm 02:15 PM
Maven project packaging step guide: Optimize the build process and improve development efficiency. As software development projects become more and more complex, the efficiency and speed of project construction have become important links in the development process that cannot be ignored. As a popular project management tool, Maven plays a key role in project construction. This guide will explore how to improve development efficiency by optimizing the packaging steps of Maven projects and provide specific code examples. 1. Confirm the project structure. Before starting to optimize the Maven project packaging step, you first need to confirm
