My custom vue directive in a .vue file is not executing - javascript

I created a Vue custom directive for the first time. But the directive is not initialized. I tried a new project and the codepen too. I really don't know the problem!
This is my Vue component:
<template>
<div id="app">
<div my-test>Some text...</div>
</div>
</template>
<script>
export default {
name: "App",
directives: {
"my-test": function(el) {
el.style.backgroundColor = "red";
console.log("This is my first directive!");
}
}
};
</script>
The sandbox:
https://codesandbox.io/s/angry-khorana-uuhd0?file=/src/App.vue
Thanks

To ensure compliance with naming standards (have a - dash in the name) and to avoid conflicts, by default, all directives registered by Vue are automatically prefixed with v-.
So change the markup to <div v-my-test>...</div>. See it working.

Related

Vue component not mounting or rendering and no error messages

I have the following 2 components
BrewTitle.vue
<template>
<h1>{{ title }}</h1>
</template>
<script>
export default {
data() {
return {
title: "Brew Title"
};
},
created() {
console.log("title created")
}
};
</script>
Snackbar.vue
<template>
<h1>{{ title }}</h1>
</template>
<script>
export default {
data() {
return {
title: "Brew Title"
};
},
created() {
console.log("snackbar created")
}
};
</script>
How they are added to the index.js file
import Vue from "vue";
import BrewTitle from "./components/BrewTitle";
import Snackbar from "./components/Snackbar";
Vue.component("brewtitle", BrewTitle);
Vue.component("snackbar", Snackbar);
const app = new Vue({
el: "#app"
});
In my html template I have the following snippet
<div id="app">
<brewtitle />
<snackbar />
</div>
<script src="main.js"></script>
The components are almost identical, but the snackbar is nowhere to be found on the html page or in the view browser extension. There are no problems with webpack and there is no message in the browser.
What am I doing wrong?
Browsers don't support self-closing tags like these:
<brewtitle />
<snackbar />
Try having explicit closing tags instead:
<brewtitle></brewtitle>
<snackbar></snackbar>
If you use a self-closing tag for a component then the browser will just treat it as an opening tag. An implicit closing tag will be created when the parent element closes. That'll work fine if there are no other siblings but it will go wrong when there are.
So taking your original code as an example:
<div id="app">
<brewtitle />
<snackbar />
</div>
The <brewtitle> won't count as closed until it reaches the closing </div>. So this is equivalent to:
<div id="app">
<brewtitle>
<snackbar></snackbar>
</brewtitle>
</div>
So <snackbar> will be treated as a child of <brewtitle>. As brewtitle doesn't have a slot the snackbar will just be discarded.
This only applies if the HTML is being parsed directly by the browser. For anything parsed by Vue itself, such as in your .vue files, this won't be a problem.
From the official Vue documentation, https://v2.vuejs.org/v2/style-guide/#Self-closing-components-strongly-recommended
Components with no content should be self-closing in single-file components, string templates, and JSX - but never in DOM templates.
...
Unfortunately, HTML doesn’t allow custom elements to be self-closing - only official “void” elements.

How to make router-link work with custom link component?

<base-link> component
I have a Vue component <base-link>, which I use every time I want to have an achor. It's mostly for applying styles specific to links, so that all the links across the whole page look the same without applying global styles.
Make <router-link> use <base-link>
When using <router-link> component to create a link, I cannot apply those styles (<base-link> styles are scoped) unless <router-link> uses my <base-link> component to create the anchor element.
Fortunately <router-link> provides tag attribute, which seems to do exactly that. Unfortunately I can't get it to work. I have 2 problems:
All my components are locally registered (I use ES6 modules with Webpack and import components locally every time I need them). <router-link> doesn't know what <base-link> component is and can't render it. Is there a way to inject a local component for <router-link> to use?
To solve problem #1, I thought it's enough to declare <base-link> component globally. Unfortunately it still doesn't work. This time <base-link> component gets rendered properly, but is still not functional - doesn't react to click events. It seems to me the problem is that it's href attribute isn't set at all. Is there a way to make <router-link> set it properly? (without setting it manually)
Question
How do I solve problems #1 and #2? I suspect #1 might be not possible, but I hope at least #2 is.
Code example
Here is a pen with code below, which illustrates both problems.
const router = new VueRouter({
routes: [
{
path: "/",
component: {
template: '<p>Homepage template</p>'
}
},
{
path: "/subpage",
component: {
template: '<p>Subpage template</p>'
}
}
]
});
// Globally registered BaseLink.
Vue.component('BaseLinkGlobal', {
props: {
href: String
},
template: `
<a
:href="href"
class="BaseLinkGlobal"
>
<slot />
</a>
`
})
const vue = new Vue({
el: "#app",
router,
components: {
// Locally registered BaseLink.
BaseLinkLocal: {
props: {
href: String
},
template: `
<a
:href="href"
class="BaseLinkLocal"
>
<slot />
</a>
`
}
},
template: `
<div>
<!-- 2 router links. One uses locally registered BaseLink
-- and the other one a globally registered one. -->
<nav>
<router-link
to="/"
tag="base-link-local"
>
Home
</router-link>
<router-link
to="/subpage"
tag="base-link-global"
>
Subpage
</router-link>
</nav>
<router-view />
</div>
`
});
You can create a base link component which can double as a normal a tag or <router-link> when you wish.
//Base link
<template>
<component :is="type" :class="{'base': type === 'a'}" v-bind="$attrs">
<slot></slot>
</component>
</template>
<script>
export default {
props: {
routerLink: {
type: Boolean,
default: false
}
},
computed: {
type() {
return this.routerLink ? 'router-link' : 'a'
}
}
}
</script>
<style scopex>
.base {
border: 1px solid red;
}
</style>
Usage
when you want to use it as a normal link just do not provide the router-link prop as below:
<base-link>This is a base a tag</base-link>
To use it as a router-link just add the router-link prop along with the to prop:
<base-link router-link to="/">This is router-link</base-link>
Explanation about the base-link component:
We use a component which is provided by vuejs to render a tag or router-link base on the truthiness of the routerLink prop.
A class of .base is added if it is a normal link i.e a
we bind $attrs which allows us to make the component more transparent i.e allows us to use attributes like href or to without passing them as props.
<base-link href="https://google.com">go to google</base-link>
You can have a look here for more explanation about usage of $attrs
This is for solving problem #2
The global component doesn't inherit the event listener of the router link. You can make it inherit by adding v-on="$listeners" to the global component.
// Globally registered BaseLink.
Vue.component('BaseLinkGlobal', {
props: {
href: String
},
template: `
<a
:href="href"
class="BaseLinkGlobal"
v-on="$listeners"
>
<slot />
</a>
`
})
The link works after adding it: https://codepen.io/jacobgoh101/pen/YvqJxL?editors=0010

Using a product tour library with VueJS

I'm trying to setup a feature intro tutorial for my web app (like intro.js). I'm having trouble with intro.js with nothing happening (no error message or tour messages). I tried setting up the data attributes that intro.js uses and calling the tour start from the mounted function on App.vue, but no luck. I'm looking to see if anyone has experience with with libraries like this combined with VueJS.
Code from App.vue:
mounted: function() {
const introJS = require('intro.js')
introJS.introJs().start()
}
Inside of the same component in it's <template>:
<div class="card card-accent-info" v-if="!isLoading" data-intro="Test step here" data-step="1">
I also have the css loaded in App.vue:
#import "~intro.js/minified/introjs.min.css";
The problem might be the way you're importing the CSS from the <style> tag. To get the styles to apply properly, import the CSS in JavaScript:
<!-- MyComponent.vue -->
<script>
import "intro.js/minified/introjs.min.css";
export default {
mounted() {
const introJS = require("intro.js");
introJS.introJs().start();
}
};
</script>
demo

Jquery and Vue, .html() is not working

I have been playing with the Vue tutorial Here and I have added a simple Jquery .html function. However it is not working. I have added the jQuery plugin, and there are no errors in the console. I have my "App" component defined like this:
<template>
<div id="app">
<div id="mainMenu"> Hello </div>
</div>
</template>
<script>
import * as start from './assets/scripts/start.js'
export default {
name: 'app',
created: start.loadMainNavigation()
}
</script>
and my loadMainNavigation function like this:
function loadMainNavigation() {
$('#mainMenu').html("ASERFDASRF");
console.log("In load Nav");
}
I can see the "In load Nav" in the console. No errors, but the DIV still has the original "Hello" - What am I doing wrong?
The reason the content doesn't change is that, at the time you are executing your function, the component has not yet been rendered to the DOM. The DOM is not rendered until the mounted event.
Beyond that, however, you need to be careful when you are integrating jQuery and Vue, or avoid it altogether. The idiomatic Vue way to do this would be something like this.
console.clear()
new Vue({
el: "#app",
data:{
message: "Hello"
},
created(){
this.message = "ASERFDASRF"
}
})
<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.3.4/vue.js"></script>
<div id="app">
<div id="mainMenu"> {{message}} </div>
</div>
There are a few times when you might mix jQuery and Vue (when you want to use a jQuery plugin for which there is no Vue counterpart, for example) but typically, there is almost always a way to do what you want without jQuery.

Vue v-on:click does not work on component

I'm trying to use the on click directive inside a component but it does not seem to work. When I click the component nothings happens when I should get a 'test clicked' in the console. I don't see any errors in the console, so I don't know what am I doing wrong.
index.html
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>vuetest</title>
</head>
<body>
<div id="app"></div>
<!-- built files will be auto injected -->
</body>
</html>
App.vue
<template>
<div id="app">
<test v-on:click="testFunction"></test>
</div>
</template>
<script>
import Test from './components/Test'
export default {
name: 'app',
methods: {
testFunction: function (event) {
console.log('test clicked')
}
},
components: {
Test
}
}
</script>
Test.vue (the component)
<template>
<div>
click here
</div>
</template>
<script>
export default {
name: 'test',
data () {
return {
msg: 'Welcome to Your Vue.js App'
}
}
}
</script>
If you want to listen to a native event on the root element of a component, you have to use the .native modifier for v-on, like following:
<template>
<div id="app">
<test v-on:click.native="testFunction"></test>
</div>
</template>
or in shorthand, as suggested in comment, you can as well do:
<template>
<div id="app">
<test #click.native="testFunction"></test>
</div>
</template>
Reference to read more about native event
I think the $emit function works better for what I think you're asking for. It keeps your component separated from the Vue instance so that it is reusable in many contexts.
// Child component
<template>
<div id="app">
<test #click="$emit('test-click')"></test>
</div>
</template>
Use it in HTML
// Parent component
<test #test-click="testFunction">
It's the #Neps' answer but with details.
Note: #Saurabh's answer is more suitable if you don't want to modify your component or don't have access to it.
Why can't #click just work?
Components are complicated. One component can be a small fancy button wrapper, and another one can be an entire table with bunch of logic inside. Vue doesn't know what exactly you expect when bind v-model or use v-on so all of that should be processed by component's creator.
How to handle click event
According to Vue docs, $emit passes events to parent. Example from docs:
Main file
<blog-post
#enlarge-text="onEnlargeText"
/>
Component
<button #click="$emit('enlarge-text')">
Enlarge text
</button>
(# is the v-on shorthand)
Component handles native click event and emits parent's #enlarge-text="..."
enlarge-text can be replaced with click to make it look like we're handling a native click event:
<blog-post
#click="onEnlargeText"
></blog-post>
<button #click="$emit('click')">
Enlarge text
</button>
But that's not all. $emit allows to pass a specific value with an event. In the case of native click, the value is MouseEvent (JS event that has nothing to do with Vue).
Vue stores that event in a $event variable. So, it'd the best to emit $event with an event to create the impression of native event usage:
<button v-on:click="$emit('click', $event)">
Enlarge text
</button>
As mentioned by Chris Fritz (Vue.js Core Team Emeriti) in VueCONF US 2019
If we had Kia enter .native and then the root element of the base input changed from an input to a label suddenly this component is broken and it's not obvious and in fact, you might not even catch it right away unless you have a really good test. Instead by avoiding the use of the .native modifier which I currently consider an anti-pattern, and will be removed in Vue 3, you'll be able to explicitly define that the parent might care about which element listeners are added to...
With Vue 2
Using $listeners:
So, if you are using Vue 2, a better option to resolve this issue would be to use a fully transparent wrapper logic. For this, Vue provides a $listeners property containing an object of listeners being used on the component. For example:
{
focus: function (event) { /* ... */ }
input: function (value) { /* ... */ },
}
and then we just need to add v-on="$listeners" to the test component like:
Test.vue (child component)
<template>
<div v-on="$listeners">
click here
</div>
</template>
Now the <test> component is a fully transparent wrapper, meaning it can be used exactly like a normal <div> element: all the listeners will work, without the .native modifier.
Demo:
Vue.component('test', {
template: `
<div class="child" v-on="$listeners">
Click here
</div>`
})
new Vue({
el: "#myApp",
data: {},
methods: {
testFunction: function(event) {
console.log('test clicked')
}
}
})
div.child{border:5px dotted orange; padding:20px;}
<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.17/vue.min.js"></script>
<div id="myApp">
<test #click="testFunction"></test>
</div>
Using $emit method:
We can also use the $emit method for this purpose, which helps us to listen to a child component's events in the parent component. For this, we first need to emit a custom event from a child component, like:
Test.vue (child component)
<test #click="$emit('my-event')"></test>
Important: Always use kebab-case for event names. For more information and a demo regading this point please check out this answer: VueJS passing computed value from component to parent.
Now, we just need to listen to this emitted custom event in the parent component, like:
App.vue
<test #my-event="testFunction"></test>
So basically, instead of v-on:click or the shorthand #click we will simply use v-on:my-event or just #my-event.
Demo:
Vue.component('test', {
template: `
<div class="child" #click="$emit('my-event')">
Click here
</div>`
})
new Vue({
el: "#myApp",
data: {},
methods: {
testFunction: function(event) {
console.log('test clicked')
}
}
})
div.child{border:5px dotted orange; padding:20px;}
<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.17/vue.min.js"></script>
<div id="myApp">
<test #my-event="testFunction"></test>
</div>
With Vue 3
Using v-bind="$attrs":
Vue 3 is going to make our life much easier in many ways. One example is that it will help us create a simpler transparent wrapper with less config, by just using v-bind="$attrs". By using this on child components, not only will our listener work directly from the parent, but also any other attributes will also work just like they would with a normal <div>.
So, with respect to this question, we will not need to update anything in Vue 3 and your code will still work fine, as <div> is the root element here and it will automatically listen to all child events.
Demo #1:
const { createApp } = Vue;
const Test = {
template: `
<div class="child">
Click here
</div>`
};
const App = {
components: { Test },
setup() {
const testFunction = event => {
console.log("test clicked");
};
return { testFunction };
}
};
createApp(App).mount("#myApp");
div.child{border:5px dotted orange; padding:20px;}
<script src="//unpkg.com/vue#next"></script>
<div id="myApp">
<test v-on:click="testFunction"></test>
</div>
But, for complex components with nested elements where we need to apply attributes and events to the <input /> instead of the parent label we can simply use v-bind="$attrs"
Demo #2:
const { createApp } = Vue;
const BaseInput = {
props: ['label', 'value'],
template: `
<label>
{{ label }}
<input v-bind="$attrs">
</label>`
};
const App = {
components: { BaseInput },
setup() {
const search = event => {
console.clear();
console.log("Searching...", event.target.value);
};
return { search };
}
};
createApp(App).mount("#myApp");
input{padding:8px;}
<script src="//unpkg.com/vue#next"></script>
<div id="myApp">
<base-input
label="Search: "
placeholder="Search"
#keyup="search">
</base-input><br/>
</div>
A bit verbose but this is how I do it:
#click="$emit('click', $event)"
UPDATE: Example added by #sparkyspider
<div-container #click="doSomething"></div-container>
In div-container component...
<template>
<div #click="$emit('click', $event);">The inner div</div>
</template>
Native events of components aren't directly accessible from parent elements. Instead you should try v-on:click.native="testFunction", or you can emit an event from Test component as well. Like v-on:click="$emit('click')".
One use case of using #click.native is when you create a custom component and you want to listen to click event on the custom component. For example:
#CustomComponent.vue
<div>
<span>This is a custom component</span>
</div>
#App.vue
<custom-component #click.native="onClick"></custom-component>
#click.native always work for this situation.
App.vue
<div id="app">
<test #itemClicked="testFunction($event)"/>
</div>
Test.vue
<div #click="$emit('itemClicked', data)">
click here
</div>
From the documentation:
Due to limitations in JavaScript, Vue cannot detect the following changes to an array:
When you directly set an item with the index, e.g. vm.items[indexOfItem] = newValue
When you modify the length of the array, e.g. vm.items.length = newLength
In my case i stumbled on this problem when migrating from Angular to VUE. Fix was quite easy, but really difficult to find:
setValue(index) {
Vue.set(this.arr, index, !this.arr[index]);
this.$forceUpdate(); // Needed to force view rerendering
}

Categories