I am quite new to VueJS and have been playing around with the framework for a couple of days.
I am building a sort of dashboard with a widget based look and feel and the problem I have is that when the user adds a lot of widgets to the dashboard, problems arise on the loading of the page since the widgets make simultaneous calls to the API's to retrieve subsets of data.
To give you a better understanding of what I am doing, the concept is the below. (This is a brief idea to keep the code clean and simple).
Home.vue
<template>
<div class="Home">
<h1>Homepage</h1>
<div v-for="w in widgets">
<component :is="widget"></component>
</div>
</div>
</template>
<script>
export default {
name: 'Home',
mounted() {
for (var i = 0; i < availableWidgets; i++) {
widgets.push(availableWidgets);
}
},
};
</script>
Widget 1
<template>
<div class="Widget1">
<span>Widget 1</span>
</div>
</template>
<script>
export default {
name: 'Widget1',
mounted() {
//Get data from API and render
},
};
</script>
Widget 2
<template>
<div class="Widget2">
<span>Widget 2</span>
</div>
</template>
<script>
export default {
name: 'Widget2',
mounted() {
//Get data from API and render
},
};
</script>
As you can see, I am sort of loading the widgets and adding them dynamically depending on what the user has in his dashboard.
The problem I have is that Widget 1 and Widget 2 (in my case there are like 20-30 widgets), will be making API calls and this works fine when 1 or 2 widgets are loaded. But once the page grows a lot and there will be like 10 widgets on the page, everything starts lagging.
What would you suggest to do to make this more performant? Is it possible to allow once component to load at a time before loading the second component and so on? I was thinking of adding async calls, but that would not stop the components from being loaded at the same time?
Looking forward to your feedback and help that you could provide.
A common pattern would be to have the first render be without data, then re-render whenever your data comes in. The browser will make sure that not too many network requests run at the same time, so you should not have lag perse from that. You just perceive lag, because your component does not render until the data loads.
I would suggest using something like Axios, which uses promises and makes it easy to create asynchronous http requests while still keeping your code readable.
<template>
<div class="widget graph">
<div v-if="loading">
<span>Loading...</span>
<img src="assets/loader.svg">
</div>
<div v-else>
<!-- Do whatever you need to do whenever data loads in -->
</div>
</div>
</template>
<script>
export default {
name: 'WidgetGraph',
data () {
return {
loading: true,
error: null,
graphData: {}
}
},
created () {
this.loadData();
},
methods: {
loadData () {
return axios.get(...).then((data) => {
this.loading = false;
}).catch(() => {
this.error = 'Something went wrong.... Panic!';
this.loading = false;
});
}
}
}
</script>
<style>
</style>
I'm trying to create a Quill.js editor instance once component is loaded using mounted() hook. However, I need to set the Quill's content using Quill.setContents() on the same mounted() hook with the data I received from vuex.store.state .
My trouble here is that the component returns empty value for the state data whenever I try to access it, irrespective of being on mounted() or created() hooks. I have tried with getters and computed properties too. Nothing seems to work.
I have included my entry.js file, concatenated all the components to make things simpler for you to help me.
Vue.component('test', {
template:
`
<div>
<ul>
<li v-for="note in this.$store.state.notes">
{{ note.title }}
</li>
</ul>
{{ localnote }}
<div id="testDiv"></div>
</div>
`,
props: ['localnote'],
data() {
return {
localScopeNote: this.localnote,
}
},
created() {
this.$store.dispatch('fetchNotes')
},
mounted() {
// Dispatch action from store
var quill = new Quill('#testDiv', {
theme: 'snow'
});
// quill.setContents(JSON.parse(this.localnote.body));
},
methods: {
setLocalCurrentNote(note) {
console.log(note.title)
return this.note = note;
}
}
});
const store = new Vuex.Store({
state: {
message: "",
notes: [],
currentNote: {}
},
mutations: {
setNotes(state,data) {
state.notes = data;
// state.currentNote = state.notes[1];
},
setCurrentNote(state,note) {
state.currentNote = note;
}
},
actions: {
fetchNotes(context) {
axios.get('http://localhost/centaur/public/api/notes?notebook_id=1')
.then( function(res) {
context.commit('setNotes', res.data);
context.commit('setCurrentNote', res.data[0]);
});
}
},
getters: {
getCurrentNote(state) {
return state.currentNote;
}
}
});
const app = new Vue({
store
}).$mount('#app');
And here is the index.html file where I'm rendering the component:
<div id="app">
<h1>Test</h1>
<test :localnote="$store.state.currentNote"></test>
</div>
Btw, I have tried the props option as last resort. However, it didn't help me in anyway. Sorry if this question is too long. Thank you for taking your time to read this. Have a nice day ;)
I will recommend the following steps to debug the above code:
In the Vue dev tools, check if the states are getting set after the network call
As you are trying to fetch data asynchronously, there can be a chance that data has not arrived when created/mounted hook is called.
Add an updated hook into your component and try to log or access the state and you should be able to see it.
Please provide the results from the above debugging, then I'll be able to add more details.
I have a PhoneCard.vue component that I'm trying to pass props to.
<template>
<div class='phone-number-card'>
<div class='number-card-header'>
<h4 class="number-card-header-text">{{ cardData.phone_number }}</h4>
<span class="number-card-subheader">
{{ cardData.username }}
</span>
</div>
</div>
</template>
<script>
export default {
props: ['userData'],
components: {
},
data() {
return {
cardData: {}
}
},
methods: {
setCardData() {
this.cardData = this.userData;
console.log(this.cardData);
}
},
watch: {
userData() {
this.setCardData();
}
}
}
The component receives a property of userData, which is then being set to the cardData property of the component.
I have another Vue.js component that I'm using as a page. On this page I'm making an AJAX call to an api to get a list of numbers and users.
import PhoneCard from './../../global/PhoneCard.vue';
export default {
components: {
'phone-card': PhoneCard
},
data() {
return {
phoneNumbers: [],
}
},
methods: {
fetchActiveNumbers() {
console.log('fetch active num');
axios.get('/api').then(res => {
this.phoneNumbers = res.data;
}).catch(err => {
console.log(err.response.data);
})
}
},
mounted() {
this.fetchActiveNumbers();
}
}
Then once I've set the response data from the ajax call equal to the phoneNumbers property.
After this comes the issue, I try to iterate through each number in the phoneNumber array and bind the value for the current number being iterated through to the Card's component, like so:
<phone-card v-for="number in phoneNumbers" :user-data="number"></phone-card>
However this leads to errors in dev tools such as property username is undefined, error rendering component, cannot read property split of undefined.
I've tried other ways to do this but they all seem to cause the same error. any ideas on how to properly bind props of a component to the current iteration object of a vue-for loop?
Try
export default {
props: ['userData'],
data() {
return {
cardData: this.userData
}
}
}
Answered my own question, after some tinkering.
instead of calling a function to set the data in the watch function, all I had to do was this to get it working.
mounted() {
this.cardData = this.userData;
}
weird, I've used the watch method to listen for changes to the props of components before and it's worked flawlessly but I guess there's something different going on here. Any insight on what's different or why it works like this would be cool!
Just a quick question.
Can you force Vue.js to reload/recalculate everything? If so, how?
Try this magic spell:
vm.$forceUpdate();
//or in file components
this.$forceUpdate();
No need to create any hanging vars :)
Update: I found this solution when I only started working with VueJS. However further exploration proved this approach as a crutch. As far as I recall, in a while I got rid of it simply putting all the properties that failed to refresh automatically (mostly nested ones) into computed properties.
More info here: https://v2.vuejs.org/v2/guide/computed.html
This seems like a pretty clean solution from matthiasg on this issue:
you can also use :key="someVariableUnderYourControl" and change the key when you want to component to be completely rebuilt
For my use case, I was feeding a Vuex getter into a component as a prop. Somehow Vuex would fetch the data but the reactivity wouldn't reliably kick in to rerender the component. In my case, setting the component key to some attribute on the prop guaranteed a refresh when the getters (and the attribute) finally resolved.
Please read this
http://michaelnthiessen.com/force-re-render/
The horrible way: reloading the entire page The terrible way:
using the v-if hack The better way: using Vue’s built-in
forceUpdate method The best way: key-changing on your
component
<template>
<component-to-re-render :key="componentKey" />
</template>
<script>
export default {
data() {
return {
componentKey: 0,
};
},
methods: {
forceRerender() {
this.componentKey += 1;
}
}
}
</script>
I also use watch: in some situations.
Try to use this.$router.go(0); to manually reload the current page.
Why?
...do you need to force an update?
Perhaps you are not exploring Vue at its best:
To have Vue automatically react to value changes, the objects must be initially declared in data. Or, if not, they must be added using Vue.set().
See comments in the demo below. Or open the same demo in a JSFiddle here.
new Vue({
el: '#app',
data: {
person: {
name: 'Edson'
}
},
methods: {
changeName() {
// because name is declared in data, whenever it
// changes, Vue automatically updates
this.person.name = 'Arantes';
},
changeNickname() {
// because nickname is NOT declared in data, when it
// changes, Vue will NOT automatically update
this.person.nickname = 'Pele';
// although if anything else updates, this change will be seen
},
changeNicknameProperly() {
// when some property is NOT INITIALLY declared in data, the correct way
// to add it is using Vue.set or this.$set
Vue.set(this.person, 'address', '123th avenue.');
// subsequent changes can be done directly now and it will auto update
this.person.address = '345th avenue.';
}
}
})
/* CSS just for the demo, it is not necessary at all! */
span:nth-of-type(1),button:nth-of-type(1) { color: blue; }
span:nth-of-type(2),button:nth-of-type(2) { color: red; }
span:nth-of-type(3),button:nth-of-type(3) { color: green; }
span { font-family: monospace }
<script src="https://unpkg.com/vue"></script>
<div id="app">
<span>person.name: {{ person.name }}</span><br>
<span>person.nickname: {{ person.nickname }}</span><br>
<span>person.address: {{ person.address }}</span><br>
<br>
<button #click="changeName">this.person.name = 'Arantes'; (will auto update because `name` was in `data`)</button><br>
<button #click="changeNickname">this.person.nickname = 'Pele'; (will NOT auto update because `nickname` was not in `data`)</button><br>
<button #click="changeNicknameProperly">Vue.set(this.person, 'address', '99th st.'); (WILL auto update even though `address` was not in `data`)</button>
<br>
<br>
For more info, read the comments in the code. Or check the docs on <b>Reactivity</b> (link below).
</div>
To master this part of Vue, check the Official Docs on Reactivity - Change Detection Caveats. It is a must read!
Use vm.$set('varName', value).
Look for details into Change_Detection_Caveats
Sure .. you can simply use the key attribute to force re-render (recreation) at any time.
<mycomponent :key="somevalueunderyourcontrol"></mycomponent>
See https://jsfiddle.net/mgoetzke/epqy1xgf/ for an example
It was also discussed here: https://github.com/vuejs/Discussion/issues/356#issuecomment-336060875
<my-component :key="uniqueKey" />
along with it use this.$set(obj,'obj_key',value)
and update uniqueKey for every update in object (obj) value
for every update this.uniqueKey++
it worked for me this way
So there's two way you can do this,
You can use $forceUpdate() inside your method handler i.e
<your-component #click="reRender()"></your-component>
<script>
export default {
methods: {
reRender(){
this.$forceUpdate()
}
}
}
</script>
You can give a :key attribute to your component and increment when want to rerender
<your-component :key="index" #click="reRender()"></your-component>
<script>
export default {
data() {
return {
index: 1
}
},
methods: {
reRender(){
this.index++
}
}
}
</script>
In order to reload/re-render/refresh component, stop the long codings. There is a Vue.JS way of doing that.
Just use :key attribute.
For example:
<my-component :key="unique" />
I am using that one in BS Vue Table Slot. Telling that I will do something for this component so make it unique.
Using v-if directive
<div v-if="trulyvalue">
<component-here />
</div>
So simply by changing the value of trulyvalue from false to true will cause the component between the div to rerender again
Dec, 2021 Update:
You can force-reload components by adding :key="$route.fullPath".
For Child Component:
<Child :key="$route.fullPath" />
For router-view tag:
<router-view :key="$route.fullPath" />
However, :key="$route.fullPath" only can force-reload the components of the different route but not the components of the same route. To be able to force-reload the components of the same route as well, we need to add "value" with an array to :key="$route.fullPath" and change "value". So it becomes :key="[$route.fullPath, value]" and we need to change "value".
*We can assign Array to :key=.
<template>
<Child
:key="[$route.fullPath, value]" // Can assign "Array" to ":key="
#childReload="reload" // Call #click="$emit('childReload')" in
/> // Child Component to increment the value.
</template>
OR OR OR OR OR OR OR OR OR OR OR OR OR OR OR OR OR OR OR OR OR OR OR OR OR
<template>
<router-view
:key="[$route.fullPath, value]" // Can assign "Array" to ":key="
#routerViewReload="reload" // Call #click="$emit('routerViewReload')"
/> // in Child Component to increment the value.
</template>
<script>
export default {
name: "Parent", components: { Child, },
data() {
return {
value: 0,
};
},
methods: {
reload() {
this.value++;
}
}
}
</script>
However, to keep using both "$route.fullPath" and "value" causes some error sometimes so only when some event like Click happens, we use both "$route.fullPath" and "value". Except when some event like Click happens, we always need to use only "$route.fullPath".
This is the final code:
<template>
<Child
:key="state ? $route.fullPath : [$route.fullPath, value]"
#childReload="reload" // Call #click="$emit('childReload')" in
/> // Child Component to increment the value.
</template>
OR OR OR OR OR OR OR OR OR OR OR OR OR OR OR OR OR OR OR OR OR OR OR OR OR
<template>
<router-view
:key="state ? $route.fullPath : [$route.fullPath, value]"
#routerViewReload="reload" // Call #click="$emit('routerViewReload')" in
/> // Child Component to increment the value.
</template>
<script>
export default {
name: "Parent", components: { Child, },
data() {
return {
state: true,
value: 0,
};
},
methods: {
reload() {
this.state = false;
this.value++;
this.$nextTick(() => this.state = true);
}
}
}
</script>
Unfortunately, there are no simple ways to force-reload components properly in Vue. That's the problem of Vue for now.
This has worked for me.
created() {
EventBus.$on('refresh-stores-list', () => {
this.$forceUpdate();
});
},
The other component fires the refresh-stores-list event will cause the current component to rerender
<router-view :key="$route.params.slug" />
Just use key with your any params its auto reload children..
I found a way. It's a bit hacky but works.
vm.$set("x",0);
vm.$delete("x");
Where vm is your view-model object, and x is a non-existent variable.
Vue.js will complain about this in the console log but it does trigger a refresh for all data. Tested with version 1.0.26.
Worked for me
data () {
return {
userInfo: null,
offers: null
}
},
watch: {
'$route'() {
this.userInfo = null
this.offers = null
this.loadUserInfo()
this.getUserOffers()
}
}
The approach of adding :key to the vue-router lib's router-view component cause's fickers for me, so I went vue-router's 'in-component guard' to intercept updates and refresh the entire page accordingly when there's an update of the path on the same route (as $router.go, $router.push, $router.replace weren't any help). The only caveat with this is that we're for a second breaking the singe-page app behavior, by refreshing the page.
beforeRouteUpdate(to, from, next) {
if (to.path !== from.path) {
window.location = to.path;
}
},
Except page reload method(flickering), none of them works for me (:key didn't worked).
and I found this method from old vue.js forum which is works for me:
https://github.com/vuejs/Discussion/issues/356
<template>
<div v-if="show">
<button #click="rerender">re-render</button>
</div>
</template>
<script>
export default {
data(){
return {show:true}
},
methods:{
rerender(){
this.show = false
this.$nextTick(() => {
this.show = true
console.log('re-render start')
this.$nextTick(() => {
console.log('re-render end')
})
})
}
}
}
</script>
Add this code:
this.$forceUpdate()
For anyone still looking around, there's a package for this now.
https://github.com/gabrielmbmb/vuex-multi-tab-state
All I had to do was install it and add it to my plugins in main.ts (as it shows on that page) and it did exactly what I wanted.
If your URL changes as well when if the component is loaded you can just use it in the :key attribute. This works especially well if you use it on the router-view tag directly. And this commes with the added benedit of the key being a value that is actually tied to the content of the page instead of just some random number.
<router-view :key="this.$route.path"></router-view>
If you are using router-view or Vue Router, you can directly use the key feature
<router-view :key="$route.path"></router-view>
This will tell the router view to re-render the page every time the path is changed.