Develop Reference

How to have data shared between Vue3 single file component instances?

I don't need to pass data between a parent component to a child one or the opposite, I need something like php/c static variables.
I want my sfc (single file component) to have some data that is shared among all instances in in the page.
As far as I understand that's why in sfc we define data as a function
export default {
data(){
return {
// props here
};
}
}
while in page scripts we can define it as an object
const app = new Vue({
data: {
// props here
},
}
That's because since we can have multiple instances of a sfc in the page defining its data as a function make each instance to execute in and get its own data, while with page script we can have a singe instance.
I need to define some of my sfc data to be shared between component instances, while other data to be per-instance.
Is there a way to do this?

That depends on the data to be defined, its complexity, and purpose.
If these are 2 or 3 readonly variables, they can be set as global properties using Vue.prototype (Vue 2) or app.config.globalProperties (Vue 3). I'm not sure, because in your example you use Vue 2 syntax.
If the data should be reactive, you can set up a simple state management as explained in the Vue documentation: Simple state management.
If the data is more complex than that, the next step will be Vuex.

Following #Igor answer I looked after the simple state management and found the ref() method that creates reactive primitive values.
In my specific use case I needed to share among all the sfc instances just an array, so in my sfc I had:
const reactive_array = ref([]);
export default {
data() {
return {
shared_array: reactive_array,
};
},
};

How to use custom object methods with Vuex?

I have several custom js objects, where I encapsulated needle logic.
So, these objects don't have relation with vuex at all, something like that:
export default class Property {
constructor(object) {
// some logic
}
addChild(property) {
// some logic
}
}
Also, I have button in my vue component, which firing vue method:
methods: {
addItem() {
this.property.addChild();
},
},
And there is problem:
this.property - it is object from vuex store.
So, when I call method in such way, I get vue error:
Error: [vuex] Do not mutate vuex store state outside mutation handlers.
Yeah, I understand, what Vue wants.
But for me it is more clear to encapsulate some complex logic in needle objects. Also, I want to use vuex for global app state.
So, please, could you share experience how to deal with vuex and custom object methods?

If you want to use vuex you simply have to use mutation to alter it's states.
So, in the the Property object's addChild function,
where you would alter state, I assume you would do it like
Store.state.xxx = 'new'
Instead of doing that, you call mutation like
Store.commit('alterState')
There's not too much difference in terms of complexity, right?

Vue2 passing arbitrary named variable as prop

I am new to Vue and after checking the docs I can not figure out how to achieve the following:
pass an arbitrarily named variable as a prop to a component instance.
From my understanding, props are meant to be a way to allow data to be passed to a component and as it states on the website:
Passing Data to Child Components with Props:
Props are custom attributes you can register on a component. When a value is passed to a prop attribute, it becomes a property on that component instance.
Since props can be required, it would seem that we can design components under the assumption that some data would be there, and possible within certain parameters (if the validator option is specified).
So I would like to define a function or object outside of vue, e.g. in an application, and pass this function or object to my vue instance.
This works if my named object of function has the exact same name as the prop to which I attempt to bind it. However, as I might have multiple instances of the Vue component and I might want to bind different data, I find using the same name for the variable less than ideal.
Now if I do as the Vue warning suggests, and name object / function the same as the prop, then the warning switches to that my data is not defined inside vue and to make sure it is reactive by reading: https://v2.vuejs.org/v2/guide/components-props.html
which, to be honest, doesnt really explain how to solve the issue,
or move the prop to the data level.
Which I can do (still gives the same warning), but kind of defeats the purpose of having props with my understanding of Vue.
This become more frustrating with anonymous vue instances.
e.g.
<script>
export default {
props: {
// records: {
// default: function(){return{}},
// type: Object
// }
},
data: function() {
return {
records: {} // define even an empty value in data for it to be 'reactive'
}
},
computed: {
fields: function() {
},
keys: function() {
return Object.keys(this.records)
}
},
methods: {
}
}
</script>
trying to use this as a component and set records to var myRecords = {"a": {}} fails:
<my-comp :records="myRecords"/>
So how exactly should I circumvent this? Where should I define my data then? and how should I handle the naming in the case of multiple instances?
A more fledged on example is found on a similar question:
Vue2: passing function as prop triggers warning that prop is already set

So I would like to define a function or object outside of vue, e.g. in an application, and pass this function or object to my vue instance.
It's hard to give a definitive answer because I don't know the specifics of how you have organized your code. Are you using Webpack? Single file components (.vue)? If yes to any of these, then you needn't use global variables in the way you have described in your question.
Your entire Vue app should consist of a single root Vue instance (which you instantiate with new Vue(...), and from there each component is rendered within the root component's template, and templates of those components, and so on.
Looking at the following template:
<my-comp :records="myRecords"/>
myRecords must be a property on the Vue component instance whose template contains the above. It could be declared within the data block, or as a computed property, or a prop, it doesn't matter.
Here's a small example:
<div id="app">
<my-comp :records="myRecords"></my-comp>
</div>
// Obtain records in some way and store it in a global variable
var records = ...
// This is the root Vue instance
new Vue({
el: '#app',
data: {
// You must store the records array in the Vue component like this
// for it to be referenced within the template.
// You can optionally transform the data first if you want.
myRecords: records.filter(r => r.name.startsWith('Bob'))
// ^ ^
// | |
// | +--- the global variable
// |
// +---- the name of the property on the component instance
}
})
Note that MyComp component does not access the records global variable in any way, it only takes its input through the records prop.

How to isolate data from Vue component in JS class?

I have a simple JS class where in the constructor I initialize dictionary. I have methods to update or delete items from this dictionary.
export default class Items {
constructor() {
this.items = {};
//Code that adds some values to it
}
save(item) {
this.items[item.id] = item;
}
delete(itemId) {
delete this.items[itemId];
}
}
And I have a Vue component where I simply output values from this dictionary with
<p v-for="item in items">{{item}}</p>
In mounted method, I create Items object and assign items dictionary to variable items from Vue data. And from Vue I call methods save or delete, I see that dictionary items in Vue data is being changed, but UI doesn't get updated. I know that I can use Vue.$delete or Vue.$set but is it possible to isolate simple JS class from Vue and keep all the data in JS class?
I'm using Vue 2.4.4

Try to use power of VueJs
...
save(item) {
Vue.set(this.items, item.id, item);
}
delete(itemId) {
let index = this.items.findIndex(p => p.id === itemId);
Vue.delete(this.items, index);
}

Is there a reason to not let Vue keep the data? It will be able to monitor it to make the most effective dom changes that way. So in proper Vue style, you should move the class logic to the component level so that that data returns the items dictionary. Then attach the save and delete as methods for the component.
For objects you only get reactivity when you edit keys that existed at render time, otherwise, you need to alert Vue a key is being added. This is done with Vue.set(this.items, item.id, item);.
If you want to separate the logic from the component you can look into vuex which allows you to create modules of state and mutations.

Angular 2 Component Factory Resolver Helper Function

I have been working with the Component Factory Resolver for awhile and while I think it's pretty slick, there is one thing that drives me nuts. I would love to wrap most of the repeated code into a helper function that renders the component.
In my case I have a dashboard component where we render quite a few different components by altering singleton services to trigger visibility or not. Rather than having a ton of these create component code blocks, I was wondering if anyone has successfully create a helper-like function that a few variables can be passed into to achieve the same effect, thus eliminating a lot of the repetitive code.
Below is my attempt at a helper function and the call to activate it. The component gets created, but the destroy function doesn't work. I have narrowed it down to the Component Reference not actually being saved to the globally accessible component. Is there a way to store component references within a global array? If so how would you go about dynamically accessing them as components are added/destroyed?
Subscription within ngOnInit
// Subscribe to Create User Modal Visibility
this._ComponentVisibilityService.createUserVisibility$.subscribe(
_createUserVisibility => {
this.renderComponent(
this.createUserModal,
CreateUserComponent,
this.createUserModalContainer,
_createUserVisibility
)
}
)
Function within the dashboard component
renderComponent(component, template, container, visibility) {
if (visibility) {
// Destroy previously built components if not already destroyed
if (component) component.destroy();
// Generate component factory
const componentFactory = this._ComponentFactoryResolver.resolveComponentFactory(template);
// Render the component
component = container.createComponent(componentFactory);
} else {
// Destroy the component if visibility is false
if (component) component.destroy()
}
}

So ended up doing some digging last night and found that Typescript considers any to be a basic (primitive) type. So from what I can tell, none of the methods, or structure are available to component, unless altered to not fit into the "basic" category, otherwise its passed as a value and not a reference. However, like in javascript, an object is not considered a primitive type so I refactored the component variable to be cast as an object with a property component as ComponentRef<any>, and it worked!
Component Property Declaration
createUserModal: { component: ComponentRef<any> } = { component: null }
Function Declaration
renderModal(component: { component: ComponentRef<any> }, template, container, visibility) {
// Create Component...
}
This combination allows the object to passed in as a reference which in turn allows the function to alter the value of DashboardComponent property this.createUserModal, which in turn allows all of the methods to be called on it as normal.