I am trying to catch situation, when component is not found, ie:
{
template: '<some-unknown-component></some-unknown-component>'
}
At that moment, Vue warns us with unknown custom element: <some-unknown-component>...
I would like to step in when some-unknown-component is not found and then use another component instead, like stub-component:
{
name: 'stub-component',
props: ['componentName'],
template: '<p>component ${componentName} does not exists, click here to create...</p>'
}
UPDATE: I am looking for solution without changing the template itself, so no v-if and component added.
Vue exposes a global error and warning handler. I managed to get a working solution by using the global warnHandler. I don't know if it is exactly what you are looking for, but it may be a good starting point. See the working snippet (I think it is quite self explanatory).
Vue.config.warnHandler = function (err, vm, info) {
if (err.includes("Unknown custom element:")) {
let componentName = err.match(/<.*>/g)[0].slice(1, -1)
vm.$options.components[componentName] = Vue.component('stub-component', {
props: ['componentName'],
template: `<p>component "${componentName}" does not exists, click here to create...</p>`,
});
vm.$forceUpdate()
} else {
console.warn(err)
}
};
new Vue({
el: '#app',
})
<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.17/vue.js"></script>
<div id="app">
<unknown-component></unknown-component>
</div>
Vue stores the details of all the registered components in the $options.component property of the Vue instance.
So, you can check for the component availability using this.$options.component and if the component is present then load the component otherwise load the other component.
In the below example, suppose you have two different components and you want to load them on the availability, then you can create a computed property on the basis of it, load the component as needed.
var CustomComponent = Vue.extend({ template: '<h2>A custom Component</h2>' });
var AnotherComponent = Vue.extend({ template: '<h2>Custom component does not exist.</h2>' });
new Vue({
el: "#app",
components: {
CustomComponent,
AnotherComponent
},
computed: {
componentAvailable () {
return this.$options.components.CustomComponent
}
}
})
<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.17/vue.js"></script>
<div id="app">
<div v-if="componentAvailable">
<custom-component />
</div>
<div v-else>
<another-component />
</div>
</div>
Related
In order to ease the styling of my page, I'd like to create a bunch of mini components like, and exploit how attributes are merged in VueJs. So for example, here is a minimal js file also hosted on this JSFiddle:
Vue.component('my-button', {
template: '<button style="font-size:20pt;"><slot></slot></button>'
})
var app = new Vue({
el: "#app",
data: {
message: "world",
},
methods: {
sayHello: function () {
alert("Hello");
}
}
})
and then in my html I just want to use <my-button> instead of button:
<div id="app">
Hello {{message}} <my-button #click="sayHello" style="color:red;">Style works, but not click</my-button> <button v-on:click="sayHello" style="color:red;">Both works</button>
</div>
Unfortunately, it seems that attributes are merged, but not listeners, so it means that I can't do v-on:click on my new button... Any way to make it possible?
Thanks!
-- EDIT --
I saw the proposition of Boussadjra Brahim of using .native, and it works, but then I found this link that explains why it's not a great practice and how to use v-on="$listeners" to map all listeners to a specific sub-button. However, I tried, to just change my template with:
template: `<button style="font-size:20pt;" v-on="$listeners"><slot></slot></button>`,
but I get an error:
Vue warn: Property or method "$listeners" is not defined on the instance but referenced during render. Make sure to declare reactive data properties in the data option."
Here is the JSFiddle.
Your fiddle didn't work because you were using an old version of Vue, $listeners was added in Vue 2.4.0.
Here's a demo:
Vue.component('my-button', {
template: '<button style="color: red" v-on="$listeners"><slot/></button>'
})
new Vue({
el: '#app',
methods: {
sayHello() {
alert('Hello')
}
}
})
<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.17/vue.js"></script>
<div id="app">
<my-button #click="sayHello">Custom Button</my-button>
<button #click="sayHello">Ordinary Button</button>
</div>
One of my root Vue.js components is using an x-template, displayed in 3 different parts of my app (3 separate Vue instances).
Everything is working if I put the data directly into the component, but I can’t figure out how to pass in data to each individual vm instance. Here’s what I’m using at present:
Vue.component('some-table', {
template: '#some-template',
data() {
return { someArray: [] }
},
methods: {
}
});
let someVm = new Vue({
el: '#some-div',
});
The template:
<script id="some-template" type="text/x-template">
<table v-for="(item, id) in someArray" v-bind:key="id">
<tr>
<td>{{item.someKey}}</td>
</tr>
</table>
</div>
</script>
Within another JavaScript class, I’m attempting to push data to someArray:
class SomeClass {
constructor() {
}
someMethod() {
let newData = [1,2,3];
someVm.someArray = newData; // doesn't work
someVm.someArray.push(...newData); // doesn't work
someVm.someArray.concat(newData); // doesn't work
}
}
Using any of the various lines in someMethod() above, I can see someVm contains someArray, but with no observers.
I can’t seem to figure out how to push new data to each instance, then be accessible within some-template. I’m obviously missing something really simple, but I’ve been stuck on this for a while now, so any pointers would be amazing!
Thanks!
Do not set data attr at component registration (Vue.component(...)). Instead, declare the props that component uses and pass it through markup or js.
Vue.config.productionTip = false;
Vue.config.devtools = false;
Vue.component('some-component', {
template: '#some-component',
props: {
message: {
type: String, // declare the props: https://vuejs.org/v2/api/#props
}
}
});
const cp1 = new Vue({
el: '#cp1',
data() {
return {
msg: "using data"
};
}
});
const cp2 = new Vue({
el: '#cp2'
});
const cp3 = new Vue({
el: '#cp3'
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.17/vue.js"></script>
<script id="some-component" type="text/x-template">
<p>{{message}}</p>
</script>
<div id="cp1">
<some-component :message="msg"></some-component>
</div>
<div id="cp2">
<some-component message="using props"></some-component>
</div>
<div id="cp3" is="some-component" message="using props and is"></div>
I'm looking for a concise example of two Vue components. The first component should contain a text input or textarea. The second component displays a character counter. I would like the first component to emit change events, and the second component should listen for those events and display its computed values (character count). I'm new to Vue and trying to wrap my head around the best way to implement this functionality. It seems rather straightforward in pure JavaScript but doing it the Vue way is not as clear to me. Thanks.
Here is how I'd do it in JavaScript:
Here's the textarea:
<textarea id="pagetext" name="pagetext"
onChange="characterCount();"
onKeyup="characterCount();">Type here</textarea>
Here's the JavaScript:
function characterCount()
{
var characters=document.myForm.pagetext.value.length;
document.getElementById('charcounter').innerHTML=characters+"";
}
My concern with Vue is passing the entire value around... for performance reasons this seems less than ideal. I may want my text editing Vue component to self-contain the value and emit the stats, ie the value for character count which would then be observed by a text stats component.
You can create a "Model" for value of textarea and provide this model to second component by using following way https://v2.vuejs.org/v2/guide/components-props.html
I've written up a snippet with four examples: your original, a simple Vue app (no components) that does the same thing, and two apps with two components that are coordinated by the parent.
The simple Vue app is actually more concise than the pure JavaScript app, and I think it shows off the reason for having a framework: your view doesn't act as a store for your program data, from which you have to pull it out.
In the final example, the parent still owns pageText, but passes it down to the my-textarea component. I like to hide the emitting behind the abstraction of a settable computed, so that the element can use v-model. Any changes are emitted up to the parent, which changes pageText, which propagates back down to the component.
I think your performance concerns fall into the realm of premature optimization, but it is possible not to use the text content as data at all, and only be concerned with the length. The fourth example does that. emitLength could have used event.target.value.length, but I wanted to use it in the mounted to initialize the length properly, so I used a ref.
function characterCount() {
var characters = document.myForm.pagetext.value.length;
document.getElementById('charcounter').innerHTML = characters + "";
}
new Vue({
el: '#app',
data: {
pageText: 'Type here'
}
});
new Vue({
el: '#app2',
data: {
pageText: 'Type here'
},
components: {
myTextarea: {
props: ['value'],
template: '<textarea name="pagetext" v-model="proxyValue"></textarea>',
computed: {
proxyValue: {
get() {
return this.value;
},
set(newValue) {
this.$emit('input', newValue);
}
}
}
},
textLength: {
props: ['value'],
template: '<div>{{value}}</div>'
}
}
});
new Vue({
el: '#app3',
data: {
textLength: null
},
components: {
myTextarea: {
template: '<textarea ref="ta" name="pagetext" #input="emitLength">Type here</textarea>',
methods: {
emitLength() {
this.$emit('change', this.$refs.ta.value.length);
}
},
mounted() {
this.emitLength();
}
},
textLength: {
props: ['value'],
template: '<div>{{value}}</div>'
}
}
});
<script src="https://unpkg.com/vue#latest/dist/vue.js"></script>
<form name="myForm">
<textarea id="pagetext" name="pagetext" onChange="characterCount();" onKeyup="characterCount();">Type here</textarea>
</form>
<div id="charcounter"></div>
<div id="app">
<h1>Vue (simple)</h1>
<form>
<textarea name="pagetext" v-model="pageText"></textarea>
</form>
<div>{{pageText.length}}</div>
</div>
<div id="app2">
<h1>Vue (with components)</h1>
<form>
<my-textarea v-model="pageText"></my-textarea>
</form>
<text-length :value="pageText.length"></text-length>
</div>
<div id="app3">
<h1>Vue emitting stats</h1>
<form>
<my-textarea #change="(v) => textLength=v"></my-textarea>
</form>
<text-length :value="textLength"></text-length>
</div>
I do not get vue components really .... I have a vue component in my html and want to show it, but it does not show anything, what do I do wrong?
What is the proper way to register and show a component in vue? Can someone give me a simple example for a beginner? :)
This is my code:
HTML
<div id="na-vue-app">
<activity-filter>
<template>
'Some Text'
</template>
</activity-filter>
</div>
Vue
new Vue({
el: '#na-vue-app'
});
const filterActivity = Vue.extend({
data: function () {
return {
distance:100,
}
},
mounted() {
},
methods: {
}
});
Vue.component('activity-filter', filterActivity);
Look at this pen: https://codepen.io/Nartub600/pen/oopBYJ
HTML
<div id="app">
<my-component msg="Hi!">
</my-component>
</div>
JS
Vue.component('my-component', {
props: ['msg'],
template: '<p>{{ msg }}</p>'
})
var app = new Vue({
el: '#app'
})
It's the easiest form to try components I think
Let's say I have a main Vue instance that has child components. Is there a way of calling a method belonging to one of these components from outside the Vue instance entirely?
Here is an example:
var vm = new Vue({
el: '#app',
components: {
'my-component': {
template: '#my-template',
data: function() {
return {
count: 1,
};
},
methods: {
increaseCount: function() {
this.count++;
}
}
},
}
});
$('#external-button').click(function()
{
vm['my-component'].increaseCount(); // This doesn't work
});
<script src="http://vuejs.org/js/vue.js"></script>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="app">
<my-component></my-component>
<br>
<button id="external-button">External Button</button>
</div>
<template id="my-template">
<div style="border: 1px solid; padding: 5px;">
<p>A counter: {{ count }}</p>
<button #click="increaseCount">Internal Button</button>
</div>
</template>
So when I click the internal button, the increaseCount() method is bound to its click event so it gets called. There is no way to bind the event to the external button, whose click event I am listening for with jQuery, so I'll need some other way to call increaseCount.
EDIT
It seems this works:
vm.$children[0].increaseCount();
However, this is not a good solution because I am referencing the component by its index in the children array, and with many components this is unlikely to stay constant and the code is less readable.
In the end I opted for using Vue's ref directive. This allows a component to be referenced from the parent for direct access.
E.g.
Have a component registered on my parent instance:
var vm = new Vue({
el: '#app',
components: { 'my-component': myComponent }
});
Render the component in template/html with a reference:
<my-component ref="foo"></my-component>
Now, elsewhere I can access the component externally
<script>
vm.$refs.foo.doSomething(); //assuming my component has a doSomething() method
</script>
See this fiddle for an example: https://jsfiddle.net/0zefx8o6/
(old example using Vue 1: https://jsfiddle.net/6v7y6msr/)
Edit for Vue3 - Composition API
The child-component has to return the function in setup you want to use in the parent-component otherwise the function is not available to the parent.
Note: <sript setup> doc is not affacted, because it provides all the functions and variables to the template by default.
You can set ref for child components then in parent can call via $refs:
Add ref to child component:
<my-component ref="childref"></my-component>
Add click event to parent:
<button id="external-button" #click="$refs.childref.increaseCount()">External Button</button>
var vm = new Vue({
el: '#app',
components: {
'my-component': {
template: '#my-template',
data: function() {
return {
count: 1,
};
},
methods: {
increaseCount: function() {
this.count++;
}
}
},
}
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.17/vue.js"></script>
<div id="app">
<my-component ref="childref"></my-component>
<button id="external-button" #click="$refs.childref.increaseCount()">External Button</button>
</div>
<template id="my-template">
<div style="border: 1px solid; padding: 2px;" ref="childref">
<p>A counter: {{ count }}</p>
<button #click="increaseCount">Internal Button</button>
</div>
</template>
For Vue2 this applies:
var bus = new Vue()
// in component A's method
bus.$emit('id-selected', 1)
// in component B's created hook
bus.$on('id-selected', function (id) {
// ...
})
See here for the Vue docs.
And here is more detail on how to set up this event bus exactly.
If you'd like more info on when to use properties, events and/ or centralized state management see this article.
See below comment of Thomas regarding Vue 3.
You can use Vue event system
vm.$broadcast('event-name', args)
and
vm.$on('event-name', function())
Here is the fiddle:
http://jsfiddle.net/hfalucas/wc1gg5v4/59/
A slightly different (simpler) version of the accepted answer:
Have a component registered on the parent instance:
export default {
components: { 'my-component': myComponent }
}
Render the component in template/html with a reference:
<my-component ref="foo"></my-component>
Access the component method:
<script>
this.$refs.foo.doSomething();
</script>
Say you have a child_method() in the child component:
export default {
methods: {
child_method () {
console.log('I got clicked')
}
}
}
Now you want to execute the child_method from parent component:
<template>
<div>
<button #click="exec">Execute child component</button>
<child-cmp ref="child"></child_cmp> <!-- note the ref="child" here -->
</div>
</template>
export default {
methods: {
exec () { //accessing the child component instance through $refs
this.$refs.child.child_method() //execute the method belongs to the child component
}
}
}
If you want to execute a parent component method from child component:
this.$parent.name_of_method()
NOTE: It is not recommended to access the child and parent component like this.
Instead as best practice use Props & Events for parent-child communication.
If you want communication between components surely use vuex or event bus
Please read this very helpful article
This is a simple way to access a component's methods from other component
// This is external shared (reusable) component, so you can call its methods from other components
export default {
name: 'SharedBase',
methods: {
fetchLocalData: function(module, page){
// .....fetches some data
return { jsonData }
}
}
}
// This is your component where you can call SharedBased component's method(s)
import SharedBase from '[your path to component]';
var sections = [];
export default {
name: 'History',
created: function(){
this.sections = SharedBase.methods['fetchLocalData']('intro', 'history');
}
}
Using Vue 3:
const app = createApp({})
// register an options object
app.component('my-component', {
/* ... */
})
....
// retrieve a registered component
const MyComponent = app.component('my-component')
MyComponent.methods.greet();
https://v3.vuejs.org/api/application-api.html#component
Here is a simple one
this.$children[indexOfComponent].childsMethodName();
I am not sure is it the right way but this one works for me.
First import the component which contains the method you want to call in your component
import myComponent from './MyComponent'
and then call any method of MyCompenent
myComponent.methods.doSomething()
Declare your function in a component like this:
export default {
mounted () {
this.$root.$on('component1', () => {
// do your logic here :D
});
}
};
and call it from any page like this:
this.$root.$emit("component1");
If you're using Vue 3 with <script setup> sugar, note that internal bindings of a component are closed (not visible from outside the component) and you must use defineExpose(see docs) to make them visible from outside. Something like this:
<script setup lang="ts">
const method1 = () => { ... };
const method2 = () => { ... };
defineExpose({
method1,
method2,
});
</script>
Since
Components using are closed by default
Sometimes you want to keep these things contained within your component. Depending on DOM state (the elements you're listening on must exist in DOM when your Vue component is instantiated), you can listen to events on elements outside of your component from within your Vue component. Let's say there is an element outside of your component, and when the user clicks it, you want your component to respond.
In html you have:
Launch the component
...
<my-component></my-component>
In your Vue component:
methods() {
doSomething() {
// do something
}
},
created() {
document.getElementById('outsideLink').addEventListener('click', evt =>
{
this.doSomething();
});
}
I have used a very simple solution. I have included a HTML element, that calls the method, in my Vue Component that I select, using Vanilla JS, and I trigger click!
In the Vue Component, I have included something like the following:
<span data-id="btnReload" #click="fetchTaskList()"><i class="fa fa-refresh"></i></span>
That I use using Vanilla JS:
const btnReload = document.querySelector('[data-id="btnReload"]');
btnReload.click();