uni-app

main.js

Environment variables

global properties

plugin usage

The project root directory must create an index.html file

Only supports using ES6 module specification

module import

module export

vuex usage

Avoid using both v-if and v-for on the same element

Expand All

The following are the points that must be adapted for migration to vue3, so that the vue2 project can run normally on vue3. For more inlistation, see the complete List of non-compatible features

# main.js

Create an application instance

// Nomae - Vue 2
import Vue from 'vue'
import App from './App'
Vue.config.productionTip = false    // vue3 不再需要
App.mpType = 'app'    // vue3 不再需要
const app = new Vue({
...App
})
app.$mount()

# Environment variables

// Configure environment variables
// Root directory .env file must start with VUE_APP_
VUE_APP_SOME_KEY = 123

// Get environment variables
process.env.NODE_ENV         // 应用运行的模式
process.env.VUE_APP_SOME_KEY // 123

Tips

Vue2 more How to set environment variables
Vue3 non-H5 end, should directly access process.env.* to obtain environment variables, does not support access to process

# global properties

For example: global network request

// Nomae - Vue 2
Vue.prototype.$http = () => {};

// after - Vue 3
const app = createApp({});
app.config.globalProperties.$http = () => {};

# plugin usage

For example: store using vuex

// Nomae - Vue 2
import store from "./store";
Vue.prototype.$store = store;

// after - Vue 3
import store from "./store";
const app = createApp(App);
app.use(store);

# The project root directory must create an index.html file

Paste and copy the following:

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta
      name="viewport"
      content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0"
    />
    <title></title>
    <!--preload-links-->
    <!--app-context-->
  </head>
  <body>
    <div id="app"><!--app-html--></div>
    <script type="module" src="/main.js"></script>
  </body>
</html>

# Only supports using ES6 module specification

commonJS needs to be changed to ES6 module specification

# module import

// Before - Vue 2, using commonJS
var utils = require("../../../common/util.js");

// After - Vue 3, only supports ES6 modules
import utils from "../../../common/util.js";

# module export

// Before - Vue 2, dependencies are exported using commonJS
module.exports.X = X;

// After - Vue 3, only supports ES6 modules
export default { X };

# vuex usage

import Vue from "vue";
import Vuex from "vuex";
Vue.use(Vuex);
const store = new Vuex.Store({
  state: {},
});
export default store;

# Avoid using both v-if and v-for on the same element

In Vue3, v-if always takes precedence over v-for. The above writing method will not meet expectations in Vue3. Due to ambiguity in syntax, it is recommended to avoid using both on the same element at the same time ([more](https://v3.cn.vuejs.org/guide/migration/ v-if-v-for.html#%E6%A6%82%E8%A7%88)).

# Life cycle adaptation

Component unload lifecycle is renamed in Vue3

destroyed changed to unmounted
beforeDestroy changed to beforeUnmount

created 和 onLoad 生命周期执行顺序

created为组件生命周期，onLoad为页面生命周期。因此created执行先于onLoad更合理。

Vue3 在实现时 created 先于 onLoad 执行；Vue2 项目由于历史包袱较重不便修改，仅在使用组合式API时与Vue3对齐。

在编写代码时不应依赖 created 和 onLoad 生命周期执行顺序

# Event adaptation

Vue3 now provides an emits option, similar to the existing props option. This option can be used to define events that a component can emit to its parent, more

**It is strongly recommended to use emits to log all events emitted by each component. **

This is especially important because the .native modifier is removed. emits will now be included in the component's $attrs when not using any listeners for declared events, which by default will be bound to the component's root node.

<template>
  <button @click="onClick">OK</button>
</template>
<script>
  export default {
    emits: ["click"],
    methods: {
      onClick() {
        this.$emit("click", "OK");
      },
    },
  };
</script>

# Some MiniApp terminal events of Vue3 project are delayed or failed to call

This can be resolved by adding the data-eventsync="true" attribute on the element that executes the event, such as:

<template>
  <button @click="onClick" data-eventsync="true">OK</button>
</template>

# v-model adaptation

Compared with Vue2, the v-model of Vue3 has undergone major changes. Multiple model can be used, and the corresponding syntax changes. More

# Modify modelValue

Vue3 v-model prop and event default names have been changed when used for custom components props.value to props.modelValue , event.value to update:modelValue

export default {
  props: {
    // value:String,
    // replace value with modelValue
    modelValue: String,
  },
};

# event return

Change the previous this.$emit('input') to this.$emit('update:modelValue') , this step will be omitted in vue3

A v-model on a custom component is equivalent to passing the modelValue prop and receiving the thrown update:modelValue event:

<ChildComponent v-model="pageTitle" />

<!-- is shorthand for: -->

<ChildComponent
  :modelValue="pageTitle"
  @update:modelValue="pageTitle = $event"
/>

If we need to change the model name, as an alternative to the model option inside the component, we can now pass an argument to v-model:

<ChildComponent v-model:title="pageTitle" />

<!-- is shorthand for: -->

<ChildComponent :title="pageTitle" @update:title="pageTitle = $event" />

# slot adaptation

Vue3 will not support the usage of slot="xxx", please use the usage of v-slot:xxx. More

<!-- Vue2 supported usage -->
<uni-nav-bar>
  <view slot="left" class="city">
    <!-- ... -->
  </view>
</uni-nav-bar>

# Filters are no longer supported

As of Vue 3.0, filters have been removed and are no longer supported, it is recommended to replace them with method calls or computed properties. More

# API `Promise` the way to call the result

In Vue3, the way the result of an API Promise call is handled is different than in Vue2. more

In Vue3, if the call is successful, it will enter the then method, and if the call fails, it will enter the catch method.
In Vue2, whether the call succeeds or fails, it will enter the then method, the first parameter of the returned data is the error object, and the second parameter is the returned data

# Conversion method

// Vue 2 to Vue 3, write the following code in main.js
function isPromise(obj) {
  return (
    !!obj &&
    (typeof obj === "object" || typeof obj === "function") &&
    typeof obj.then === "function"
  );
}

uni.addInterceptor({
  returnValue(res) {
    if (!isPromise(res)) {
      return res;
    }
    return new Promise((resolve, reject) => {
      res.then((res) => {
        if (res[0]) {
          reject(res[0]);
        } else {
          resolve(res[1]);
        }
      });
    });
  },
});

# Composition API usage of lifecycle hooks

In the Vue3 composite API, it is also necessary to follow the uni-app life cycle hook specification. For example, the application life cycle such as onLaunch can only be monitored in App.vue. Please pay attention to the scope of application of the life cycle hook when using it. View all lifecycle hooks

You can only use life cycle hooks in the <script setup> single-file syntax sugar or the setup() method. Take page A jumping to page B and passing parameters as an example:

Method 1

Method 2

//uni.navigateTo({
//  url: 'xxx?id=1&name=uniapp'
//})

// Method 1: On page B<script setup>
<script setup>
  import {
    onLoad,
    onShow
  } from "@dcloudio/uni-app";

  // onLoad accepts the parameters passed by the A page
  onLoad((option) => {
    console.log("B 页面 onLoad:", option); //B 页面 onLoad: {id: '1', name: 'uniapp'}
  });

  onShow(() => {
    console.log("B 页面 onShow");
  });
</script>

# `$mp` adjusted to `$scope`

In Vue3, $mp under this object is adjusted to $scope

# Using Vuex in nvue

In Vue3, if nvue uses the related API of Vuex, you need to return the Vuex example in the return value of createApp in main.js:

import Vuex from "vuex";
export function createApp() {
  const app = createSSRApp(App);
  app.use(store);
  return {
    app,
    Vuex, // 如果 nvue 使用 vuex 的各种map工具方法时，必须 return Vuex
  };
}

# Need to actively open sourcemap

App, applet-side source code debugging, you need to actively open sourcemap in vite.config.js

import { defineConfig } from "vite";
import uni from "@dcloudio/vite-plugin-uni";

/**
 * @type {import('vite').UserConfig}
 */

export default defineConfig({
  build: {
    sourcemap: true,
  },

  plugins: [uni()],
});

# 小程序平台

# 监听原生的点击事件

In the applet platform of vue3, you can use tap first to listen for native click events. In vue3, the .native modifier is removed, so the compiler cannot predict whether click is going to trigger a native event or a custom event of the component, so it is not converted into a tap event of the applet.

# style

vue3 出于性能考虑，style 中暂不支持 div、p 等 HTML 标签选择器，推荐使用 class 选择器，template 中的 HTML 标签仍会进行转换。

# 真机调试

vue3 微信开发者工具真机调试页面空白，如帖子
vue3 微信小程序真机调试，如帖子

均可以通过在 manifest.json 的 mp-weixin 中配置 minified 为 true 来解决

{
  "mp-weixin": {
    "setting": {
      // ...其他配置
      "minified": true
    }
  }
}

# What is the minimum mobile phone version supported by vue3?

The range supported by vue3 is: Android > 4.4 (depending on the version of the system webview, the native Android system has been upgraded to the system webview generally 5.0, and the domestic Android system generally needs 7.0 or more when the x5 kernel is not used), ios >= 10

Android < 4.4, configure X5 kernel support, it needs to be downloaded online for the first time, you can configure to start the application after downloading the X5 kernel successfully, Details

# vue3 nvue does not support the recycle-list component

vue3 nvue does not support the recycle-list component

# When the h5 platform is released, tree shaking will be enabled by default

When vue3 is released on the h5 platform, in order to optimize the size of the package, tree shaking will be started by default, and only the explicitly used api will be packaged. If you want to turn off tree shaking, you can configure it in manifest.json:

"h5": {
    "optimization": {
        "treeShaking": {
            "enable": false
        }
    }
}

# Get page parameters through props

New in vue3 platform: use props to get page parameters

<script setup>
  // The page can directly receive the parameters passed in by the url by defining props
  // As：uni.navigateTo({ url: '/pages/index/index?id=10' })
  const props = defineProps({
    id: String,
  });
  console.log("id=" + props.id); // id=10
</script>

<script>
  // The page can directly receive the parameters passed in by the url by defining props
  // As：uni.navigateTo({ url: '/pages/index/index?id=10' })
  export default {
    props: {
      id: {
        type: String,
      },
    },
    setup(props) {
      console.log("id=" + props.id); // id=10
    },
  };
</script>

# The applet and the App do not support the interpolation method to define internationalization

Due to the limitation of the operating platform, the interpolation method is currently not supported on the applet and App side to define internationalization. Messages Functions need to be used to define internationalization information. [Reference Document](https://vue-i18n.intlify.dev/guide/advanced/ function.html)

Example:

const messages = {
  en: {
    greeting: ({ named }) => `hello, ${named('name')}!`
  }
}

products

HBuilderX uni-app uniCloud uniMPsdk 5+Runtime uni-id uni-search uniPay uniPush uni-verify sms uni-starter uni-admin uni-upgrade-center uni-im uni-ai uni-cms

Operating services

uni-AD uni-stat uni-portal Safety topic

Developer Services

forum dashboard

Docs

uni-app uniCloud native-support HBuilderX

Ecosystem

Marketplace OAuth

About： DCloud Jobs Terms of service Privacy policy acceptable use policy

# main.js

# Environment variables

# global properties

# plugin usage

# The project root directory must create an index.html file

# Only supports using ES6 module specification

# module import

# module export

# vuex usage

# Avoid using both v-if and v-for on the same element

# Life cycle adaptation

# Event adaptation

# Some MiniApp terminal events of Vue3 project are delayed or failed to call

# v-model adaptation

# Modify modelValue

# event return

# slot adaptation

# Filters are no longer supported

# API Promise the way to call the result

# Conversion method

# Composition API usage of lifecycle hooks

# $mp adjusted to $scope

# Using Vuex in nvue

# Need to actively open sourcemap

# 小程序平台

# 监听原生的点击事件

# style

# 真机调试

# What is the minimum mobile phone version supported by vue3?

# vue3 nvue does not support the recycle-list component

# When the h5 platform is released, tree shaking will be enabled by default

# Get page parameters through props

# The applet and the App do not support the interpolation method to define internationalization

On This Page

# API `Promise` the way to call the result

# `$mp` adjusted to `$scope`