今天做项目的时候发现要用到watch来监听，所以就学习了watch的装饰器写法，然后顺便把之前用过的都看了，这里做一个简单的回顾
类型
多种装饰器和一个函数（Mixins）
@Prop@PropSync@Model@Watch@Provide@Inject@ProvideReactive@InjectReactive@Emit@Ref-
@Component(由 vue-class-component提供) -
Mixins(辅助函数名为mixins，由 vue-class-component提供)
@Prop
@Prop(options: (PropOptions | Constructor[] | Constructor) = {})
import { Vue, Component, Prop } from 'vue-property-decorator'
@Component
export default class YourComponent 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 {
props: {
propA: {
type: Number
},
propB: {
default: 'default value'
},
propC: {
type: [String, Boolean]
}
}
}
Tips:
如果要type根据类型定义设置每个prop值的属性，则可以使用reflect-metadata。
- 设置
emitDecoratorMetadata到true。 - 导入
reflect-metadata之前先导入vue-property-decorator（reflect-metadata只需导入一次。）
import 'reflect-metadata'
import { Vue, Component, Prop } from 'vue-property-decorator'
@Component
export default class MyComponent extends Vue {
@Prop() age!: number
}
每个 prop's 默认值需要定义为与上面显示的示例代码相同。
不支持 @Prop() prop = 'default value' .
@PropSync
@PropSync(propName: string, options: (PropOptions | Constructor[] | Constructor) = {})
import { Vue, Component, PropSync } from 'vue-property-decorator'
@Component
export default class YourComponent extends Vue {
@PropSync('name', { type: String }) syncedName!: string
}
相当于
export default {
props: {
name: {
type: String
}
},
computed: {
syncedName: {
get() {
return this.name
},
set(value) {
this.$emit('update:name', value)
}
}
}
}
除此之外，它的工作方式与@Prop将propName作为装饰器的参数的工作方式不同，此外，它还在幕后创建了一个计算的getter和setter。这样可以与该属性进行交互，因为它是常规数据属性，同时使其与.sync在父组件中附加修饰符一样容易。这个装饰器其实个人认为用处不是那么大，毕竟直接使用修饰符就好。
@Model
@Model(event?: string, options: (PropOptions | Constructor[] | Constructor) = {})
import { Vue, Component, Model } from 'vue-property-decorator'
@Component
export default class YourComponent extends Vue {
@Model('change', { type: Boolean }) readonly checked!: boolean
}
相当于
export default {
model: {
prop: 'checked',
event: 'change'
},
props: {
checked: {
type: Boolean
}
}
}
@Modelproperty也可以通过定义其类型定义中的属性reflect-metadata设置type。
@Watch
@Watch(path: string, options: WatchOptions = {}) decorator
import { Vue, Component, Watch } from 'vue-property-decorator'
@Component
export default class YourComponent 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
@Provide(key?: string | symbol) / @Inject(options?: { from?: InjectKey, default?: any } | InjectKey) decorator
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' },
[symbol]: symbol
},
data() {
return {
foo: 'foo',
baz: 'bar'
}
},
provide() {
return {
foo: this.foo,
bar: this.baz
}
}
})
@ProvideReactive
@ProvideReactive(key?: string | symbol) / @InjectReactive(options?: { from?: InjectKey, default?: any } | InjectKey) decorator
这些是 @Provide和 @Inject的被动版本.如果提供的值被父组件修改，则子组件可以捕获此修改。
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)
The functions decorated by @Emit $emit their return value followed by their original arguments. If the return value is a promise, it is resolved before being emitted.
这个函数是由@Emit $emit他们的返回值和原始参数所修饰的。如果返回值是一个promise，则在返回之前将其解析。
如果未通过event参数提供事件的名称，则使用函数名称。在这种情况下，camelCase名称将转换为kebab-case。
import { Vue, Component, Emit } from 'vue-property-decorator'
@Component
export default class YourComponent extends Vue {
count = 0
@Emit()
addToCount(n: number) {
this.count += n
}
@Emit('reset')
resetCount() {
this.count = 0
}
@Emit()
returnValue() {
return 10
}
@Emit()
onInputChange(e) {
return e.target.value
}
@Emit()
promise() {
return new Promise(resolve => {
setTimeout(() => {
resolve(20)
}, 0)
})
}
}
相当于
export default {
data() {
return {
count: 0
}
},
methods: {
addToCount(n) {
this.count += n
this.$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
import { Vue, Component, Ref } from 'vue-property-decorator'
import AnotherComponent from '@/path/to/another-component.vue'
@Component
export default class YourComponent 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
}
}
}
}