How to resolve '[Vue warn]: Multiple root nodes returned' error

How to solve the "[Vue warn]: Multiple root nodes returned" error

When using Vue.js to develop web applications, you often encounter various All kinds of errors. One of the common errors is "[Vue warn]: Multiple root nodes returned". This error usually occurs when using Vue's template syntax, indicating that multiple root nodes are returned in a component.

In Vue, a root node refers to the content directly wrapped in a tag in a component template. For example, in the template of a Vue component, there can usually only be one root node, as shown below:

<template>
  <div>
    <!-- 这是根节点 -->
    <h1>标题</h1>
    <p>正文内容</p>
  </div>
</template>

However, sometimes we accidentally return multiple root nodes in the template, causing Vue to throw "[Vue warn]: Multiple root nodes returned" error. This situation usually occurs in the following situations:

1. Multiple root-level elements are used in the template:

<template>
  <h1>标题1</h1>
  <h2>标题2</h2>
</template>

2. are used in the template Vue's conditional rendering or loop rendering instructions resulted in the generation of multiple elements:

<template>
  <div v-if="condition">
    <h1 v-for="item in items">{{ item }}</h1>
  </div>
</template>

3. The use of Vue's slots in the template resulted in the generation of multiple elements:

<template>
  <div>
    <slot name="header"></slot>
    <slot name="content"></slot>
  </div>
</template>

No matter what the situation is, when multiple root nodes are returned in the template, Vue will throw a "[Vue warn]: Multiple root nodes returned" error.

In order to solve this error, we need to ensure that there is only one root node in the template. Here are several common solutions:

1. Use <template> tags to wrap multiple root-level elements:

<template>
  <template>
    <h1>标题1</h1>
    <h2>标题2</h2>
  </template>
</template>

2. Use the <div> tag to wrap multiple elements:

<template>
  <div>
    <h1>标题1</h1>
    <h2>标题2</h2>
  </div>
</template>

3. When using conditional rendering or loop rendering instructions, ensure that only one root-level element is rendered :

<template>
  <div v-if="condition">
    <h1>{{ title }}</h1>
  </div>
</template>

4. When using slots, wrap multiple slot contents in one element:

<template>
  <div>
    <div>
      <slot name="header"></slot>
    </div>
    <div>
      <slot name="content"></slot>
    </div>
  </div>
</template>

With the above solution, we can Avoid the occurrence of "[Vue warn]: Multiple root nodes returned" errors and ensure the normal operation of Vue applications.

To summarize, when using Vue.js, we need to pay special attention to returning only one root node in the template. If the "[Vue warn]: Multiple root nodes returned" error occurs, we can use <template>, <div> or reasonable refactoring code to solve this problem . In this way, we can develop and run Vue applications smoothly.

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