目前在用vue开发的项目中，都会配合使用TypeScript进行一些约束。为了提高开发效率，往往会使用装饰器来简化我们的代码。

本文主要介绍装饰器vue-property-decorator 和 vux-class的使用。

1. 安装

npm i -S vue-property-decorator
npm i -S vuex-class

2. vue-property-decorator

• @Component
• @Prop
• @PropSync
• @Model
• @ModelSync
• @Watch
• @Provide
• @Inject
• @ProvideReactive
• @InjectReactive
• @Emit
• @Ref
• @VModel

@Component

import { Vue, Component } from 'vue-property-decorator'

@Component({
 components:{
      componentA,
      componentB,
  }
})
export default class MyComponent extends Vue{
   
}

相当于：

export default{
  name: 'MyComponent',
  components:{
    componentA,
    componentB,
  }
}

@Prop

@Prop(options: (PropOptions | Constructor[] | Constructor) = {}) decorator

表示：@Prop装饰器接收一个参数，这个参数可以有三种写法：

• PropOptions：可以使用以下选项：type，required，default，validator
• Constructor：例如String，Number，Boolean等，指定 prop 的类型
• Constructor[]：指定 prop 的可选类型

例如：

import { Vue, Component, Prop } from 'vue-property-decorator'
 
@Component
export default class MyComponent extends Vue {
  @Prop(Number) readonly propA: number | undefined
  @Prop({ default: 'default value' }) readonly propB!: string
  @Prop([String, Boolean]) readonly propC: string | boolean | undefined
}

相当于：

export default {
  name: 'MyComponent',
  props: {
    propA: {
      type: Number,
    },
    propB: {
      default: 'default value',
    },
    propC: {
      type: [String, Boolean],
    },
  },

@PropSync

@PropSync(propName: string, options: (PropOptions | Constructor[] | Constructor) = {}) decorator

• propName 表示父组件传递过来的属性名
• 父组件要结合.sync来使用

例如：

// child.vue
import { Vue, Component, PropSync } from 'vue-property-decorator'
 
@Component
export default class MyComponent extends Vue {
  @PropSync('name', { type: String }) syncedName!: string

<!-- parent.vue -->
<template>
  <div>
    <MyComponent  :name.sync="name" />
  </div>
</template>

相当于：

export default {
  name: 'MyComponent',
  props: {
    name: {
      type: String,
    },
  },
  computed: {
    syncedName: {
      get() {
        return this.name
      },
      set(value) {
        this.$emit('update:name', value)
      },
    },
  },
}

@PropSync的工作原理与@Prop类似，除了接受propName作为装饰器的参数之外，它还在幕后创建了一个计算的getter和setter。通过这种方式，您可以像使用常规数据属性一样使用该属性，同时像在父组件中添加.sync修饰符一样简单。

@Model

@Model装饰器允许我们在一个组件上自定义v-model。

@Model(event?: string, options: (PropOptions | Constructor[] | Constructor) = {}) decorator

例如：

import { Vue, Component, Model } from 'vue-property-decorator'
 
@Component
export default class MyComponent extends Vue {
  @Model('change', { type: Boolean }) readonly checked!: boolean
}

相当于：

export default {
  model: {
    prop: 'checked',
    event: 'change',
  },
  props: {
    checked: {
      type: Boolean,
    },
  },
}

@ModelSync

@ModelSync(propName: string, event?: string, options: (PropOptions | Constructor[] | Constructor) = {}) decorator

例如：

import { Vue, Component, ModelSync } from 'vue-property-decorator'
 
@Component
export default class MyComponent extends Vue {
  @ModelSync('checked', 'change', { type: Boolean }) readonly checkedValue!: boolean
}

相当于：

export default {
  model: {
    prop: 'checked',
    event: 'change',
  },
  props: {
    checked: {
      type: Boolean,
    },
  },
  computed: {
    checkedValue: {
      get() {
        return this.checked
      },
      set(value) {
        this.$emit('change', value)
      },
    },
  },
}

@Watch

@Watch(path: string, options: WatchOptions = {}) decorator

例如：

import { Vue, Component, Watch } from 'vue-property-decorator'
 
@Component
export default class MyComponent extends Vue {
  @Watch('child')
  onChildChanged(val: string, oldVal: string) {}
 
  @Watch('person', { immediate: true, deep: true })
  onPersonChanged1(val: Person, oldVal: Person) {}
 
  @Watch('person')
  onPersonChanged2(val: Person, oldVal: Person) {}
}

相当于：

export default {
  watch: {
    child: [
      {
        handler: 'onChildChanged',
        immediate: false,
        deep: false,
      },
    ],
    person: [
      {
        handler: 'onPersonChanged1',
        immediate: true,
        deep: true,
      },
      {
        handler: 'onPersonChanged2',
        immediate: false,
        deep: false,
      },
    ],
  },
  methods: {
    onChildChanged(val, oldVal) {},
    onPersonChanged1(val, oldVal) {},
    onPersonChanged2(val, oldVal) {},
  },
}

@Provide | @Inject

@Provide(key?: string | symbol) decorator
@Inject(options?: { from?: InjectKey, default?: any } | InjectKey) decorator

例如：

import { Component, Inject, Provide, Vue } from 'vue-property-decorator'
 
const symbol = Symbol('baz')
 
@Component
export class MyComponent extends Vue {
  @Inject() readonly foo!: string
  @Inject('bar') readonly bar!: string
  @Inject({ from: 'optional', default: 'default' }) readonly optional!: string
  @Inject(symbol) readonly baz!: string
 
  @Provide() foo = 'foo'
  @Provide('bar') baz = 'bar'
}

相当于：

const symbol = Symbol('baz')
 
export const MyComponent = Vue.extend({
  inject: {
    foo: 'foo',
    bar: 'bar',
    optional: { from: 'optional', default: 'default' },
    baz: symbol,
  },
  data() {
    return {
      foo: 'foo',
      baz: 'bar',
    }
  },
  provide() {
    return {
      foo: this.foo,
      bar: this.baz,
    }
  },
})

@ProvideReactive | @InjectReactive

它们是@provider和@Inject的响应式版本。如果父组件修改了提供的值，那么子组件可以捕捉到这种修改。

@ProvideReactive(key?: string | symbol)  decorato
@InjectReactive(options?: { from?: InjectKey, default?: any } | InjectKey) decorator

例如：

const key = Symbol()
@Component
class ParentComponent extends Vue {
  @ProvideReactive() one = 'value'
  @ProvideReactive(key) two = 'value'
}
 
@Component
class ChildComponent extends Vue {
  @InjectReactive() one!: string
  @InjectReactive(key) two!: string
}

@Emit

@Emit(event?: string) decorator

例如：

import { Vue, Component, Emit } from 'vue-property-decorator'
 
@Component
export default class MyComponent extends Vue {
  count = 0
 
  @Emit()
  addToCount(n: number) {
    this.count += n
  }
 
  @Emit('reset')
  resetCount() {
    this.count = 0
  }
 
  @Emit()
  returnValue() {
    return 10
  }
 
  @Emit()
  onInputChange(e) {
    return e.target.value
  }
 
  @Emit()
  promise() {
    return new Promise((resolve) => {
      setTimeout(() => {
        resolve(20)
      }, 0)
    })
  }
}

相当于：

export default {
  data() {
    return {
      count: 0,
    }
  },
  methods: {
    addToCount(n) {
      this.count += n
      this.$emit('add-to-count', n)
    },
    resetCount() {
      this.count = 0
      this.$emit('reset')
    },
    returnValue() {
      this.$emit('return-value', 10)
    },
    onInputChange(e) {
      this.$emit('on-input-change', e.target.value, e)
    },
    promise() {
      const promise = new Promise((resolve) => {
        setTimeout(() => {
          resolve(20)
        }, 0)
      })
 
      promise.then((value) => {
        this.$emit('promise', value)
      })
    },
  },
}

@Ref

Ref(refKey?: string) decorator

例如：

import { Vue, Component, Ref } from 'vue-property-decorator'
 
import AnotherComponent from '@/path/to/another-component.vue'
 
@Component
export default class MyComponent extends Vue {
  @Ref() readonly anotherComponent!: AnotherComponent
  @Ref('aButton') readonly button!: HTMLButtonElement
}

相当于：

export default {
  computed() {
    anotherComponent: {
      cache: false,
      get() {
        return this.$refs.anotherComponent as AnotherComponent
      }
    },
    button: {
      cache: false,
      get() {
        return this.$refs.aButton as HTMLButtonElement
      }
    }
  }
}

@VModel

@VModel(propsArgs?: PropOptions) decorator

例如：

import { Vue, Component, VModel } from 'vue-property-decorator'
 
@Component
export default class MyComponent extends Vue {
  @VModel({ type: String }) name!: string
}

相当于：

export default {
  props: {
    value: {
      type: String,
    },
  },
  computed: {
    name: {
      get() {
        return this.value
      },
      set(value) {
        this.$emit('input', value)
      },
    },
  },
}

3. vuex-class

• @State
• @Getter
• @Action
• @Mutation
• namespace

import Vue from 'vue'
import Component from 'vue-class-component'
import {
  State,
  Getter,
  Action,
  Mutation,
  namespace
} from 'vuex-class'

const someModule = namespace('path/to/module')

@Component
export class MyComponent extends Vue {
  @State('foo') stateFoo
  @State(state => state.bar) stateBar
  @Getter('foo') getterFoo
  @Action('foo') actionFoo
  @Mutation('foo') mutationFoo
  @someModule.Getter('foo') moduleGetterFoo

  // 如果省略参数, 直接使用每一个 state/getter/action/mutation 类型的属性名称
  @State foo
  @Getter bar
  @Action baz
  @Mutation qux

  created () {
    this.stateFoo // -> store.state.foo
    this.stateBar // -> store.state.bar
    this.getterFoo // -> store.getters.foo
    this.actionFoo({ value: true }) // -> store.dispatch('foo', { value: true })
    this.mutationFoo({ value: true }) // -> store.commit('foo', { value: true })
    this.moduleGetterFoo // -> store.getters['path/to/module/foo']
  }
}