# Global API

# createApp

Returns an application instance which provides an application context. The entire component tree mounted by the application instance share the same context.

const app = Vue.createApp({})
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You can chain other methods after createApp, they can be found in Application API

# Arguments

The function receives a root component options object as a first parameter:

const app = Vue.createApp({
  data() {
    return {
      ...
    }
  },
  methods: {...},
  computed: {...}
  ...
})
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With the second parameter, we can pass root props to the application:

const app = Vue.createApp(
  {
    props: ['username']
  },
  { username: 'Evan' }
)
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<div id="app">
  <!-- Will display 'Evan' -->
  {{ username }}
</div>
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# Typing

interface Data {
  [key: string]: unknown
}

export type CreateAppFunction<HostElement> = (
  rootComponent: PublicAPIComponent,
  rootProps?: Data | null
) => App<HostElement>
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# h

Returns a returns "virtual node", usually abbreviated to VNode: a plain object which contains information describing to Vue what kind of node it should render on the page, including descriptions of any child nodes. It is intended for manually written render functions:

render() {
  return Vue.h('h1', {}, 'Some title')
}
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# Arguments

Accepts three arguments: tag, props and children

# tag

  • Type: String | Object | Function | null

  • Details:

    An HTML tag name, a component, an async component or null. Using null would render a comment. This parameter is required

# props

  • Type: Object

  • Details:

    An object corresponding to the attributes, props and events we would use in a template. Optional

# children

  • Type: String | Array | Object

  • Details:

    Children VNodes, built using h(), or using strings to get "text VNodes" or an object with slots. Optional

    h('div', {}, [
      'Some text comes first.',
      h('h1', 'A headline'),
      h(MyComponent, {
        someProp: 'foobar'
      })
    ])
    
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# defineComponent

Implementation-wise defineComponent does nothing but return the object passed to it. However, in terms of typing, the returned value has a synthetic type of a constructor for manual render function, TSX and IDE tooling support.

# Arguments

An object with component options

import { defineComponent } from 'vue'

const MyComponent = defineComponent({
  data() {
    return { count: 1 }
  },
  methods: {
    increment() {
      this.count++
    }
  }
})
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# defineAsyncComponent

Creates an async component that will be loaded only when it's necessary.

# Arguments

For basic usage, defineAsyncComponent can accept a factory function returning a Promise. Promise's resolve callback should be called when you have retrieved your component definition from the server. You can also call reject(reason) to indicate the load has failed.

import { defineAsyncComponent } from 'vue'

const AsyncComp = defineAsyncComponent(() =>
  import('./components/AsyncComponent.vue')
)

app.component('async-component', AsyncComp)
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When using local registration, you can also directly provide a function that returns a Promise:

import { createApp, defineAsyncComponent } from 'vue'

createApp({
  // ...
  components: {
    AsyncComponent: defineAsyncComponent(() =>
      import('./components/AsyncComponent.vue')
    )
  }
})
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For advanced usage, defineAsyncComponent can accept an object:

The defineAsyncComponent method can also return an object of the following format:

import { defineAsyncComponent } from 'vue'

const AsyncComp = defineAsyncComponent({
  // The factory function
  loader: () => import('./Foo.vue')
  // A component to use while the async component is loading
  loadingComponent: LoadingComponent,
  // A component to use if the load fails
  errorComponent: ErrorComponent,
  // Delay before showing the loading component. Default: 200ms.
  delay: 200,
  // The error component will be displayed if a timeout is
  // provided and exceeded. Default: Infinity.
  timeout: 3000,
  // A function that returns a boolean indicating whether the async component should retry when the loader promise rejects
  retryWhen: error => error.code !== 404,
  // Maximum allowed retries number
  maxRetries: 3,
  // Defining if component is suspensible
  suspensible: false
})
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See also: Dynamic and Async components

# resolveComponent

WARNING

resolveComponent can only be used within render or setup functions.

Allows resolving a component by its name, if it is available in the current application instance.

Returns a Component or undefined when not found.

const app = Vue.createApp({})
app.component('MyComponent', {
  /* ... */
})
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import { resolveComponent } from 'vue'
render() {
  const MyComponent = resolveComponent('MyComponent')
}
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# Arguments

Accepts one argument: component

# component

  • Type: String

  • Details:

    The name of a loaded component.

# resolveDynamicComponent

WARNING

resolveDynamicComponent can only be used within render or setup functions.

Allows resolving a component by the same mechanism that <component :is=""> employs.

Returns the resolved Component or a newly created VNode with the component name as the node tag. Will raise a warning if the Component was not found.

import { resolveDynamicComponent } from 'vue'
render () {
  const MyComponent = resolveDynamicComponent('MyComponent')
}
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# Arguments

Accepts one argument: component

# component

  • Type: String | Object (component’s options object)

  • Details:

    For more details, refer to the documentation on Dynamic Components.

# resolveDirective

WARNING

resolveDirective can only be used within render or setup functions.

Allows resolving a directive by its name, if it is available in the current application instance.

Returns a Directive or undefined when not found.

const app = Vue.createApp({})
app.directive('highlight', {})
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import { resolveDirective } from 'vue'
render () {
  const highlightDirective = resolveDirective('highlight')
}
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# Arguments

Accepts one argument: name

# name

  • Type: String

  • Details:

    The name of a loaded directive.

# withDirectives

WARNING

withDirectives can only be used within render or setup functions.

Allows applying directives to a VNode. Returns a VNode with the applied directives.

import { withDirectives, resolveDirective } from 'vue'
const foo = resolveDirective('foo')
const bar = resolveDirective('bar')

return withDirectives(h('div'), [
  [foo, this.x],
  [bar, this.y]
])
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# Arguments

Accepts two arguments: vnode and directives.

# vnode

  • Type: vnode

  • Details:

    A virtual node, usually created with h().

# directives

  • Type: Array

  • Details:

    An array of directives.

    Each directive itself is an array, which allows for up to 4 indexes to be defined as seen in the following examples.

    • [directive] - The directive by itself. Required.
    const MyDirective = resolveDirective('MyDirective')
    const nodeWithDirectives = withDirectives(
      h('div'), 
      [ [MyDirective] ]
    )
    
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    • [directive, value] - The above, plus a value of type any to be assigned to the directive
    const MyDirective = resolveDirective('MyDirective')
    const nodeWithDirectives = withDirectives(
      h('div'), 
      [ [MyDirective, 100] ]
    )
    
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    • [directive, value, arg] - The above, plus a String argument, ie. click in v-on:click
    const MyDirective = resolveDirective('MyDirective')
    const nodeWithDirectives = withDirectives(
      h('div'), 
      [ [MyDirective, 100, 'click'] ]
    )
    
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    • [directive, value, arg, modifiers] - The above, plus a key: value pair Object defining any modifiers.
    const MyDirective = resolveDirective('MyDirective')
    const nodeWithDirectives = withDirectives(
      h('div'), 
      [ [MyDirective, 100, 'click', { prevent: true }] ]
    )
    
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# createRenderer

The createRenderer function accepts two generic arguments: HostNode and HostElement, corresponding to Node and Element types in the host environment.

For example, for runtime-dom, HostNode would be the DOM Node interface and HostElement would be the DOM Element interface.

Custom renderers can pass in the platform specific types like this:

import { createRenderer } from 'vue'
const { render, createApp } = createRenderer<Node, Element>({
  patchProp,
  ...nodeOps
})
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# Arguments

Accepts two arguments: HostNode and HostElement

# HostNode

  • Type: Node

  • Details:

    The node in the host environment.

# HostElement

  • Type: Element

  • Details:

    The element in the host environment.

# nextTick

Defer the callback to be executed after the next DOM update cycle. Use it immediately after you’ve changed some data to wait for the DOM update.

import { createApp, nextTick } from 'vue'

const app = createApp({
  setup() {
    const message = ref('Hello!')
    const changeMessage = async newMessage => {
      message.value = newMessage
      await nextTick()
      console.log('Now DOM is updated')
    }
  }
})
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See also: $nextTick instance method

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Last updated: 7/23/2020, 10:22:10 AM