Being create Menu components use to frameless windows. but I don't know how to bind events into slot. I want to build structure like this
in WindowBar.vue
<template>
<div>
<app-menu-bar>
<app-menu label="File"></app-menu>
</app-menu-bar>
</div>
</temaplte>
in AppMenuBar.vue (name is app-menu-bar)
<template>
<section>
<slot
v-bind:onSelected="onSelected"
v-on:doClick="doClick"
>
</slot>
</section>
</template>
<script>
export default {
name: 'app-menu-bar',
data () {
return {
onSelected: ''
}
}
}
</script>
in AppMenu.vue (name is app-menu)
<template>
<section class="menu">
<button
v-on:click="doClick"
v-bind:class="isSelected"
>
{{ label }}
</button>
</section>
</template>
<script>
export default {
name: 'app-menu',
props: {
label: String
},
computed: {
isSelected () {
// This is binding data from AppMenuBar
return this.onSelected == this.label ? 'selected' : ''
}
},
methods: {
doClick () {
this.$emit('doClick', this.label)
}
},
mounted () {
console.log(this.onSelected) // it is undefined
}
}
</script>
how do i binding data into slot, like this.onSelected?
You can't listen to events on <slot>. The more detailed answer you can read here https://github.com/vuejs/vue/issues/4332.
In your case, I will suggest putting all business logic in the parent component (which is WindowBar.vue). After that, you can have control of your child's component events and props. Or, if there is some specific situation, and you want to pass events through nested components you can use the event bus for it. More about the event bus you can read here: https://www.digitalocean.com/community/tutorials/vuejs-global-event-bus
I'm making a todo app in vue.js which has a component TodoItem
<template>
<div class="todo-item" v-bind:class="{'is-completed':todo.completed}">
<p>
<input type="checkbox" #change="markCompleted" />
{{todo.task}}
<button class="del">x</button>
</p>
</div>
</template>
<script>
export default {
name: "TodoItem",
props: ["todo"],
methods: {
markCompleted() {
this.todo.completed = true
},
},
};
</script>
todo prop that I'm passing:
{
id:1,
task:'todo 1',
completed:false
}
but it is throwing an error error Unexpected mutation of "todo" prop
Method 1 (Vue 2.3.0+) - From your parent component, you can pass prop with sync modifier
Parent Component
<TodoItem v-for="todo in todoList" :key="todo.id" todo_prop.sync="todo">
Child Component
<template>
<div class="todo-item" v-bind:class="{'is-completed':todo.completed}">
<p>
<input type="checkbox" #change="markCompleted" />
{{todo.task}}
<button class="del">x</button>
</p>
</div>
</template>
<script>
export default {
name: "TodoItem",
props: ["todo_prop"],
data() {
return {
todo: this.todo_prop
}
},
methods: {
markCompleted() {
this.todo.completed = true
},
},
};
</script>
Method 2 - Pass props from parent component without sync modifier and emit an event when the value changed. For this method, everything else is similar as well. Just need to emit an event when the todo item changed to completed.
The code is untested. Apologies if anything does not work.
What happen ? : Mutating a prop locally is now considered an anti-pattern, e.g. declaring a prop and then setting this.myProp = 'someOtherValue' in the component. Due to the new rendering mechanism, whenever the parent component re-renders, the child component’s local changes will be overwritten.
Solution : You can storage it as local data.
export default {
name: "TodoItem",
props: ["todo"],
data() {
return {
todoLocal: this.todo,
};
},
methods: {
markComplete() {
this.todoLocal.completed = !this.todoLocal.completed;
},
},
};
For me to fix this problem I store props in todos data im watching brad vue tutorials and i get this error this is my actual codes and its working.
<template>
<div class="todo-item" v-bind:class="{ 'is-complete': todo.completed }">
<p>
<input
type="checkbox"
v-on:change="markComplete(todo.completed)"
v-bind:checked="todo.completed"
/>
{{ todo.title }}
<!-- <button #click="$emit('del-todo', todo.id)" class="del">x</button> -->
</p>
</div>
</template>
<script>
export default {
name: 'TodoItem',
props: ['todo'],
data() {
return {
todos: this.todo,
}
},
methods: {
markComplete(isComplete) {
this.todos.completed = !isComplete
},
},
}
</script>
<style scoped>
.todo-item {
background: #f4f4f4;
padding: 10px;
border-bottom: 1px #ccc dotted;
}
.is-complete {
text-decoration: line-through;
}
.del {
background: #ff0000;
color: #fff;
border: none;
padding: 5px 9px;
border-radius: 50%;
cursor: pointer;
float: right;
}
</style>
One of the core principles of VueJS is that child components never mutate a prop.
All props form a one-way-down binding between the child property and the parent one: when the parent property updates, it will flow down to the child, but not the other way around.
If you wish to have the child component update todo.completed, you have two choices:
Use .sync modifier (Recommended)
This approach will require a bit of change to your props. You can read more about it here.
Parent component
<template>
<div>
...
<todo-item :task="nextTodo.task" :completed.sync="nextTodo.completed"/>
</div>
</template>
Child component
<template>
<div class="todo-item" v-bind:class="{'is-completed':completed}">
<p>
<input type="checkbox" #change="markCompleted" />
{{task}}
<button class="del">x</button>
</p>
</div>
</template>
<script>
export default {
name: "TodoItem",
props: ["task", "completed"],
methods: {
markCompleted() {
this.$emit('update:completed', true)
},
},
};
</script>
Use a custom event
Vue allows you set up listeners in your parent for events that the child will emit. Your child component can use this mechanism to ask the parent to change things. In fact, the above .sync modifier is doing exactly this behind the scenes.
Parent component
<template>
<div>
...
<todo-item :todo="nextTodo" #set-completed="$value => { nextTodo.completed = $value }/>
</div>
</template>
Child component
<template>
<div class="todo-item" v-bind:class="{'is-completed':todo.completed}">
<p>
<input type="checkbox" #change="markCompleted" />
{{todo.task}}
<button class="del">x</button>
</p>
</div>
</template>
<script>
export default {
name: "TodoItem",
props: ["todo"],
methods: {
markCompleted() {
this.$emit('set-completed', true)
},
},
};
</script>
You can't change a prop from inside a component - they are meant to be set by the parent only. It's a one-directional communication path.
You can try one of two things - either move your logic for detecting a todo has been completed to the parent, or feed the prop into a new variable in the data() lifecycle hook (this will only happen when the component is loaded for the first time, so you won't be able to update from outside the component, if that's important for your use case).
The canonical way to achieve n-deep prop binding in Vue 3 is to wrap your prop with a simple computed property. This is an example of a component that will communicate changes to it's selected property to it's parent--who is ultimately responsible for storing the state.
<template>
<!-- In this example my-child-component also has a "selected" prop -->
<my-child-component v-model:selected="syncSelectedId" />
</template>
<script lang="ts">
export default defineComponent({
components: { MyChildComponent },
props: {
selected: {
type: String,
required: true,
}
},
emits: ['update:selected'],
setup(props, context) {
const syncSelectedId = computed<string>({
get() {
return props.selected;
},
set(newVal: string) {
context.emit('update:selected', newVal);
},
});
return {
syncSelectedId,
}
}
});
So to re-iterate: With this strategy the highest level parent is the holder of the state. The code above assumes that there is a parent component in the hierarchy (so this component is just a "middle-man").
Then my-child-component can simply emit its own update:selected event to cause the state to change. That child will be updated appropriately through it's prop after the emit event causes the parent chain to propagate that change up (through emits) and then back down the component hierarchy (through props).
If you wanted to you could modify the code above to make it the "owner" of the state:
<template>
<my-child-component v-model:selected="selected" />
</template>
<script lang="ts">
export default defineComponent({
components: { MyChildComponent },
setup(props, context) {
const selected = ref('');
return {
selected,
}
}
});
And now of course you won't run into the "Unexpected mutation of X prop" error.
Another option is to have a prop that serves as a "default value" for a given state:
<template>
<my-child-component v-model:selected="selected" />
</template>
<script lang="ts">
export default defineComponent({
components: { MyChildComponent },
props: {
defaultSelected: {
type: String,
required: false,
default: ''
}
},
setup(props, context) {
const selected = ref(props.defaultSelected);
return {
selected,
}
}
});
And in this code above keep in mind that selected will NOT change if defaultSelected changes after the component has been initialized.
And lastly it's worth noting that you could write more sophisticated code to detect if a property is supplied--and if not use an internal state variable to store the value. I use this pattern for re-usable components that could be embedded in places where the parent wants to control the state OR in places where the parent is happy to delegate the storage of the state to the child:
<template>
<!-- In this example my-child-component also has a "selected" prop -->
<my-child-component v-model:selected="syncSelectedId" />
</template>
<script lang="ts">
export default defineComponent({
components: { MyChildComponent },
props: {
selected: {
type: String,
required: false,
default: null // Important: parent MUST pass non-null value if it wants to control state
}
},
emits: ['update:selected'],
setup(props, context) {
// This is state storage used if prop.selected is not provided
const _selected = ref('');
const syncSelectedId = computed<string>({
get() {
return props.selected === null ? _selected.value : props.selected;
},
set(newVal: string) {
if (props.selected !== null) {
// Using prop.selected as the driving model...
if (newVal !== props.selected) {
// We need to set to empty string (never null)
context.emit('update:selectedId', (newVal == null ? '' : newVal));
}
} else { // Storing selection state with _selectedId
if (newVal !== _selected.value) {
_selected.value = newVal == null ? '' : newVal;
context.emit('update:selected', _selected);
}
}
},
});
return {
syncSelectedId,
}
}
});
This last example is tricky... it gives special meaning to null and requires that you be very mindful of potential values of your state. In my example empty string is my representation for "no selection" and null is used as a flag for "no parent model of this state".
Mainly, property mutation is now deprecated and parent properties are overwritten when the parent component renders its DOM.
Here's the official documentation about it. We can still achieve this in multiple possible ways. Through a data property, a computed property, and component events.
When we want to pass this value back to the parent component as well as the nested child component of the current child component, using a data property would be useful as shown in the following example.
Example:
Calling your child component from the parent component like this.
Parent component:
<template>
<TodoItem :todoParent="todo" />
</template>
<script>
export default {
data() {
return {
todo: {
id:1,
task:'todo 1',
completed:false
}
};
}
}
</script>
Child component:
<template>
<div class="todo-item" v-bind:class="{'is-completed':todo.completed}">
<p>
<input type="checkbox" #change="markCompleted" />
{{todo.task}}
<button class="del">x</button>
</p>
</div>
</template>
<script>
export default {
name: "TodoItem",
props: ["todoParent"],
data() {
return {
todo: this.todoParent,
};
},
methods: {
markCompleted() {
this.todo.completed = true
},
},
};
</script>
Even you can pass this property to the nested child component and it won't give this error/warning.
Other use cases when you only need this property sync between parent and child component. It can be achieved using the sync modifier from Vue. v-model can also be useful. Many other examples are available in this question thread.
Example2: using component events.
We can emit the event from the child component as below.
Parent component:
<template>
<TodoItem :todo="todo" #markCompletedParent="markCompleted" />
</template>
<script>
export default {
data() {
return {
todo: {
id:1,
task:'todo 1',
completed:false
}
};
},
methods: {
markCompleted() {
this.todo.completed = true
},
}
}
</script>
Child component:
<template>
<div class="todo-item" v-bind:class="{'is-completed':todo.completed}">
<p>
<input type="checkbox" #change="markCompleted" />
{{todo.task}}
<button class="del">x</button>
</p>
</div>
</template>
<script>
export default {
name: "TodoItem",
props: ["todo"],
methods: {
markCompleted() {
this.$emit('markCompletedParent', true)
},
}
};
</script>
While you can still custom-bind events to handle this, .sync property extensions are considered deprecated. In Vue3 (at least) you can and usually should use the v-model:property declaration, similar to how you bind the property to the actual input. You just need to bind the inner input with :value and have it emit a matching update:property
<!-- CustomInput.vue -->
<script setup>
defineProps(['modelValue'])
defineEmits(['update:modelValue'])
</script>
<template>
<input
:value="modelValue"
#input="$emit('update:modelValue', $event.target.value)"
/>
</template>
And use thusly:
<CustomInput v-model="searchText" />
I want to change vue.js data outside the default export statement. Given the example below, how would I go about doing that?
<template>
<div>
<h6 class="font-weight-normal mb-3">{{ name }}</h6>
</div>
</template>
<script>
export default {
data() {
return {
name: ""
}
}
}
let changeName = (name) => {
//How do I change the name data property here
}
</script>
If you assign the component to a variable/constant, you should be able to simply trigger the proxy setter of the data object or with component-level methods.
const component = new Vue({
data() {
return {
name: "Initial value."
}
},
methods: {
changeName(newName) {
this.name = newName;
}
}
});
// Mount it to an element (for demo purposes)
component.$mount('#app');
document.getElementById('btn-setter').onclick = function() {
component.name = 'Changed with SETTER';
};
document.getElementById('btn-method').onclick = function() {
component.changeName('Changed with METHOD');
};
// Uncomment this to start exporting it.
// export default component;
<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.17/vue.js"></script>
<div id="app">
<h6 class="font-weight-normal mb-3">{{ name }}</h6>
<button id="btn-setter">Change with setter</button>
<button id="btn-method">Change with method</button>
</div>
You can write any function you want in the page outside of the component (or export statement) but you would need to invoke it in your methods section or somewhere in the component. I use this for functions that create default values, instead of importing them from outside just write a function initVal = () => someVal then in the data or computed or somewhere reference initVal (no this).
I would like to retrieve all input values from my child components (client and advice, seen below), but not sure how to proceed.
client.vue
<template>
<div id="client">
<input type="text" v-model="client.name" />
<input type="text" v-model="client.code" />
</div>
</template>
<script>
export default {
data() {
return {
client: {
name: '',
code: '',
}
}
}
}
</script>
advice.vue
<template>
<div id="advice">
<input type="text" v-model="advice.foo" />
<input type="text" v-model="advice.bar" />
<div v-for="index in 2" :key="index">
<input type="text" v-model="advice.amount[index]" />
</div>
</div>
</template>
<script>
export default {
data() {
return {
advice: {
foo: '',
bar: '',
amount:[]
}
}
}
}
</script>
Each component has more fields than the above example.
My home page (parent) looks as simple as:
<template>
<form id="app" #submit="printForm">
<clientInfo />
<advice />
<input type="submit" value="Print" class="btn" />
</form>
</template>
<script>
import clientInfo from "#/components/clientInfo.vue";
import advice from "#/components/advice.vue";
export default {
components: {
clientInfo,
advice
},
methods: {
printForm() {}
}
}
</script>
My first idea was to $emit, but not sure how to do that efficiently with more than 20 fields without attaching a #emitMethod="parentEmitMethod" to every single field.
My second idea was to have a Vuex store (as seen below), but I don't know how to save all the states at once and not sure if I should.
new Vuex.Store({
state: {
client: {
name:'',
code:''
},
advice: {
foo:'',
bar:'',
amount:[]
}
}
})
You could use FormData to get the values of the form's <input>s or <textarea>s that have a name attribute (anonymous ones are ignored). This works even if the form has nested Vue components that contain <input>s.
export default {
methods: {
printForm(e) {
const form = e.target
const formData = new FormData(form) // get all named inputs in form
for (const [inputName, value] of formData) {
console.log({ inputName, value })
}
}
}
}
demo
You could use v-model with your custom components. Let's say you want to use them like this:
<advice v-model="adviceData"/>
For this, you would need to watch for value changes on your input elements inside your advice component and then emit an input event with the values. This will update the adviceData binded property. One generic way to do this could be including a watcher inside your advice component, like this:
export default {
data() {
return {
advice: {
foo: '',
bar: '',
amount:[]
}
}
},
watch: {
advice: {
handler: function(newValue, oldValue) {
this.$emit('input', newValue);
},
deep: true,
}
},
}
This way you will not have to add a handler for each input field. The deep option must be included if we need to detect changes on nested data in the advice object.
I think you can achieve what you want is when the user writes something using#change this will trigger a method when the input value is changed, you could use a button instead or anything you want, like this:
The child component
<input type="text" v-model="advice.amount[index]" #change="emitCurrStateToParent ()"/>
You gotta add #change="emitCurrStateToParent ()" in every input you have.
emitCurrStateToParent () {
this.$emit("emitCurrStateToParent", this.advice)
}
Then in you parent component
<child-component v-on:emitCurrStateToParent="reciveDataFromChild ($event)"></child-component>
reciveDataFromChild (recivedData) {
// Do something with the data
}
I would use a button instead of #change, like a "Save" button idk, the same goes for vuex, you can use the #change event
saveDataAdviceInStore () {
this.$store.commit("saveAdvice", this.advice)
}
Then in the store
mutations: {
saveAdvice (state, advice) {
state.advice = advice
}
}
The grid component grid.js:
<template>
<div class="grid">
...
<component v-for="c in cells" :is="c.componentName"></component>
</div>
</template>
<script>
export default {
props: {
cells: { type: Array, required: true }
}
methods: {
// the idea what I need
reEmitAllCellComponentEventWithPrefix($event) {
// add prefix
this.$emit("cell-" + $event.name, $event.data);
}
}
}
</script>
The base-cell component base-cell.js (define common cell props and methods):
export default {
props: ['componentName', 'columnIndex', 'rowIndex', 'cellData', ...],
...
}
The custom-cell component custom-cell.js (all extend from base-cell component, register global):
<template>
<dom ...>
</template>
<script>
import baseCell from "./base-cell"
export default {
extends: baseCell,
props: {
componentName: '...',
customProp1: '...',
...
},
watch: {
// a custom event example
customProp1(){
this.$emit('custom-event1', ...)
}
},
...
}
</script>
All the cell components has its own custom events, maybe any event-name.
The usage:
// dom
<div id="app">
<grid :cells="cells" #cell-custom-event1="customCellEventHandler"></grid>
</div>
// js
import grid from "./grid"
new Vue({
el: '#app',
data: { cells: ... },
method: {
customCellEventHandler($event){
...
}
},
...
})
I wanna user can listen on cell component's custom event with prefix cell- when use grid component. How can I make this work?
You can do it like this:
<template>
<div class="row">
<component v-for="c in cells" :is="c.componentName" #click="onClick(c.name, c.data)"></component>
</div>
</template>
<script>
export default {
props: {
cells: { type: Array, required: true }
}
methods: {
onClick(name, data) {
this.$emit("cell-" + name, data);
}
}
}
</script>
Basically when you look through the cells and create the elements, you add a click event for each cell and add whatever parameters you want, and use them to emit the event.
If you also need the "event" data you can add $event in #click="onClick(c.name, c.data)" like this #click="onClick(c.name, c.data, $event)" and then you can add on the method the respective paramater onClick(name, data, e)
I hope this was what you were looking for.