vue.js 2 use scoped slots in custom element - javascript

I'll try to explain my problem.
I have a VueJS component, that uses slots in its template. For example:
App.vue:
<template>
<div>
<slot name="content" :content="somecontent"></slot>
</div>
</template>
<script>
export default {
data(){
return {
somecontent: "test"
}
}
}
</script>
And now I would like to initialize it like this:
<App>
<template #content="somecontent">
<div>{{somecontent}}</div>
</template>
</App>
The idea is that the user would be able to override a part of the widget content and still have some data that the widget provides. A real-life example would be a list where the elements are being loaded remotely and the user can override the list item template.
I know now that custom elements do not support scoped slots. Is there any other way to achieve this? The template syntax does not need to be like above.
Thanks for any info that could solve my problem.

Related

best alternative for <slot/> in <textarea> in [ Vue.js 3 ] component

I want create component with textarea and pass data inside that like
<c-textarea> hello world </c-textarea>
but the classic <slot/> tag not work inside of textarea
what's simplest and cleanest alternative
<template>
<textarea><slot/></textarea>
</template>
in Vue.js 3
You should use value & input to bind the content instead of using slot
Here is the updated version of CTextarea component
<template>
<textarea :value="modelValue" #input="$emit('update:modelValue', $event.target.value)">
</textarea>
</template>
<script>
export default {
name: 'CTextarea',
emits: ['update:modelValue'],
props: {
modelValue: String,
},
};
</script>
check this woking demo
You can extract the content of a slot:
<template>
<textarea>{{ $slots.default ? $slots.default()[0].children : ''}}</textarea>
</template>
Basically, this builds the slot manually, which gives you a VNode element, where children contains the slot content.
I would really try to find another way though, this is coarse, error prone and most likely not what you want to do.
Personally, I would stick to the v-model approach.

Vue doesnt update component on dynamic variable condition change

I am working with Vuejs. I want to render components based on value of variable val.
My component looks like this
<template v-if="this.$val===1">
<component1 />
</template>
<template v-if="this.$val===2">
<component2 />
</template>
I have defined a global variable val using Vue.prototype and I am updating it using onclick function,where I am changing value of val to 2 but after clicking it doesnt show component2 instead of component 1.
Define val globally in main.js using following line of code
Vue.prototype.$val = 1;
Can someone please help me with this. Thanks
td,dr; Vue.prototypeis not reactive.
I'm going to enumerate issues as I observe them, hoping you'll find them useful.
You're not specifying which version of Vue you're using. Since you're using Vue.prototype, I'm going to guess you're using Vue 2.
Never use this in a <template>.
Inside templates, this is implicit (sometimes formulated: "inside templates this doesn't exist"). What would be this.stuff in controller, is stuff in the template.
You can't conditionally swap the top level <template> of a Vue component. You need to take the conditional either one level up or one level down:
one level up would be: you create separate components, one for each template; declare them and have the v-if in their parent component, rendering one, or the other
one level down would be: you move the v-if inside the top level <template> tag of the component. Example:
<template><!-- top level can't have `v-if` -->
<div v-if="val === 1">
val is 1
<input v-model="val">
</div>
<div v-else>
val is not 1
<input v-model="val">
</div>
</template>
<script>
export default {
data: () => ({ val: 1 })
}
</script>
Note <template> tags don't render an actual tag. They're just virtual containers which help you logically organise/group their contents, but what gets rendered is only their contents.1 So I could have written the above as:
<template><!-- top level can't have v-if -->
<template v-if="val === 1">
<div>
val is 1
<input v-model="val">
</div>
</template>
<template v-else>
<template>
<template>
<div>
val is not 1
<input v-model="val">
</div>
</template>
</template>
</template>
</template>
And get the exact same DOM output.
For obvious reasons, <template> tags become useful when you're working with HTML structures needing to meet particular parent/child constraints (e.g: ul + li, tr + td, tbody + tr, etc...).
They're also useful when combining v-if with v-for, since you can't place both on a single element (Vue needs to know which structural directive has priority, since applying them in different order could produce different results).
Working example with what you're trying to achieve:
Vue.prototype.$state = Vue.observable({ foo: true })
Vue.component('component_1', {
template: `
<div>
This is <code>component_1</code>.
<pre v-text="$state"/>
<button #click="$state.foo = false">Switch</button>
</div>
`})
Vue.component('component_2', {
template: `
<div>
This is <code>component_2</code>.
<pre v-text="$state"/>
<button #click="$state.foo = true">Switch back</button>
</div>
`})
new Vue({
el: '#app'
})
<script src="https://unpkg.com/vue#2.7.10/dist/vue.min.js"></script>
<div id="app">
<component_1 v-if="$state.foo"></component_1>
<component_2 v-else></component_2>
</div>
Notes:
<div id="app">...</div> acts as <template> for the app instance (which is, also, a Vue component)
Technically, I could have written that template as:
<div id="app">
<template v-if="$state.foo">
<component_1 />
</template>
<template v-else>
<component_2 />
</template>
</div>
, which is pretty close to what you were trying. But it would be slightly more verbose than what I used, without any benefit.
I'm using a Vue.observable()2 for $state because you can't re-assign a Vue global. I mean, you can, but the change will only affect Vue instances created after the change, not the ones already created (including current one). In other words, Vue.prototype is not reactive. This, most likely, answers your question.
To get past the problem, I placed a reactive object on Vue.prototype, which can be updated without being replaced: $state.
1 - there might be an exception to this rule: when you place text nodes inside a <template>, a <div> wrapper might be created to hold the text node(s). This behaviour might not be consistent across Vue versions.
2 - Vue.Observable() was added in 2.6.0. It's a stand-alone export of Vue's reactivity module (like a component's data(), but without the component). In v3.x Vue.Observable() was renamed Vue.reactive(), to avoid confusion/conflation with rxjs's Observable.
global variables are accessed in template without this keyword which means $val===1 will work.
Solution 1:
<template>
<component1 v-if='$val === 1' />
<component2 v-else/>
</template>
This will work.
But you could make use of dynamic components in your case.
Solution 2:
<template>
<component :is='currentComponent'/>
</template>
<script>
\\imports of your components will go here
export default {
name: 'app',
components: {
component1, component2
},
computed:{
currentComponent(){
return this.$val === 1?component1:component2;
}
}
}
</script>
Dynamic components are more performant and helps you maintain state of component.

How can I output the <template /> tag to the DOM in Vue.js

I have a custom library built on Stencil that I need to integrate with Vue, and this library relies on the browser's <template /> tag.
For example, I need to render the following code to the dom:
<my-custom-list>
<template>
<my-custom-title></my-custom-title>
<my-custom-description></my-custom-description>
</template>
</my-custom-list>
my-custom-list will then get whatever is inside the template and use it for each of the items in the list.
I managed to get it to work by using the v-html directive, for example:
<my-custom-list v-html="<template><my-custom-title></my-custom-title><my-custom-description></my-custom-description></template>">
</my-custom-list>
However, I would also like to be able to use Vue components inside this template tag, like:
<my-custom-list>
<template>
<my-custom-title></my-custom-title>
<my-custom-description></my-custom-description>
<custom-vue-component></custom-vue-component>
</template>
</my-custom-list>
Some old answers online suggest using the is directive to be able to output the template tag, like <div is="template"> but that has been deprecated.
I am not even sure if this is possible, but any insights would be much appreciated.
You can use the v-pre directive to skip compilation for parts of your components.
<my-custom-list v-pre>
<template>
<my-custom-title></my-custom-title>
<my-custom-description></my-custom-description>
<custom-vue-component></custom-vue-component>
</template>
</my-custom-list>

When mixing Blaze with React, is there a way to pass in code from the html file as a react child?

I have an app that uses both Blaze and React, and we are slowly refactoring out the Blaze, but for the foreseeable future we will still have both.
I currently have a simple blaze template which has been changed into a React component. The template looks something like this:
<template name="myTemplate">
<div>
<h1>{{someTitle}}</h1>
<div>
{{> Template.contentBlock}}
</div>
</div>
</template>
The equivalent component currently looks like this:
export default class MyComponent extends React.Component {
static propTypes = {
someTitle: PropTypes.string.isRequired
}
render () {
return (
<div>
<h1>{this.props.someTitle}</h1>
<div>
{this.props.children}
</div>
</div>
)
}
}
The usage of the Template within another html file looks something like this:
<div>
Some Stuff
<div>
{{#myTemplate someTitle="Some Title"}}
<div>
More stuff within to go within my template
</div>
{{/myTemplate}}
</div>
</div>
What I am currently trying to do is get rid of myTemplate and replace it with MyComponent. Usually this could easily be done by simply putting in {{> React component=MyComponent someTitle="Some Title"}}, but for this case since I have content within the template that probably has to be passed in as the component's children, I am not sure how it should be done.
So the question becomes, how can I pass in that content that is to be rendered within the template to the React component? Is there any way around this?

Polymer 1.0+, can't define template in light dom for use by component

In Polymer 1.0+, how do you pass in a template from the light dom to be used in the dom-module? I'd like the template in the light dom to have bind variables, then the custom element use that template to display its data.
Here is an example of how it would be used by the component user:
<weather-forecast days="5" as="day">
<template id="forecast-template">
<img src="{{day.weatherpic}}">
<div>{{day.dayofweek}}</div>
<div>{{day.wordy}}</div>
<div>{{day.highlowtemp}}</div>
</template>
</weather-forecast>
This weather-forecast component would contain an iron-list in the dom-module and ideally, the component would reference the "forecast-template" inside the iron-list that would bind the variables to the element. Ultimately, it would generate a 5-day forecast using that template. My issue is that I haven't seen an example of bind-passing variable based templates into a Polymer 1.0 custom element. I would think this or something similar would be fairly commonplace.
The following is an example of how I would like to see it work on the client side, but no luck yet. Although the template is successfully references, it only displays once, while other fields actually do show in the loop.
<dom-module id="weather-forecast">
<template is="dom-bind">
<iron-list items="[[days]]" as="day">
<content selector='#forecast-template'"></content>
</iron-list>
</template>
</dom-module>
Any input is appreciated. Thanks!
You cannot use dom-bind inside another polymer element.
Your first element should just be dom-bind
<template is="dom-bind">
<iron-list items="[[days]]" as="day">
<weather-forecast day=[[day]]></weather-forecast>
</iron-list>
</template>
Your second element should be weather-forecast
<dom-module id="weather-forecast">
<template>
<style></style>
<img src="{{day.weatherpic}}">
<div>{{day.dayofweek}}</div>
<div>{{day.wordy}}</div>
<div>{{day.highlowtemp}}</div>
</template>
<script>
Polymer({
is: "weather-forecast",
properties: {
day: {
type: Object
}
}
});
</script>
</dom-module>
If this does not work, try wrapping the weather-forecast tag inside a template tag inside iron-list.
You can use the Templatizer. You can look at my blog for some example (there's also a Plunker link).
Unfortunately there seems to be some bug or limitation, which breaks two way binding:
Add a "dynamic" element with data-binding to my polymer-element
Polymer: Updating Templatized template when parent changes
Two way data binding with Polymer.Templatizer

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