Adding JavaScript to StenclJS Listen event - javascript

I want to change the background of my component when the window is scrolled down, and I tried implementing it this way but it doesnt work. Any guidance would be helpful!
export class NewsContainer{
#Listen('scroll', { target: 'window' })
handleScroll(ev) {
var newsContainer= document.querySelector(".newsContainer");
newsContainer.classList.remove("transparentBackground");
newsContainer.classList.add("darkBackground");
}
render(){
return [
<div class="newsContainer transparentBackground">Content</div>
]
}
}
I get the following error:
news-container.entry.js:9 Uncaught TypeError: Cannot read property 'classList' of null
at NewsContainer.handleScroll

The problem I faced from time to time is that some hooks or listener are executed before the elements are rendered and available in the DOM tree (the render function is called). That can lead to a termination of the JavaScript in order to stop the application. I bet this is exactly why you get this error. So a simple if condition should be sufficient like:
#Listen('scroll', { target: 'window' })
handleScroll(ev) {
var newsContainer= document.querySelector(".newsContainer");
if(newsContainer && newsContainer.classList){
newsContainer.classList.remove("transparentBackground");
newsContainer.classList.add("darkBackground");
}
}
I would go a step further and use references since I think it looks a bit clearer and has the charme that you are independent of classNames. and you can access the element from every method and validate a bit easier:
export class NewsContainer{
private element;
#Listen('scroll', { target: 'window' })
handleScroll(ev) {
if(!this.element) return;
this.element.classList.remove("transparentBackground");
this.element.classList.add("darkBackground");
}
render(){
return [
<div ref={(el) => {this.element = el}} class="newsContainer transparentBackground">Content</div>
]
}
}
You can use this.element which refers to your div element.

Related

Using ngClass on an element that uses getElementById, element is null

I've got an html element with overflow: auto, but I want to give it a border only when it's scrollable.
How do I evaluate the element's size from within ngClass without getting any kind of null errors?
Note: The element's enclosing div doesn't get rendered until after getting a response from an observable.
Attempt 1:
The html element is set up like this:
<div ngIf="!loading">
<div id="{{someID}}" [ngClass]="{'border-class': isScrollable}"> ... </div>
</div>
In my ngOnInit, I call a function to see if the given element can be scrolled.
ngOnInit() {
// this.loading gets set to false after an observable is returned
/* ... */
// scroll check
let e = document.getElementById(`${this.someID}`);
if (element !== null) {
this.isScrollable = e.scrollHeight > e.clientHeight;
}
}
If I don't check for null, I get errors. If I do check for null, then even if I have scrollable content, when the page is loaded, the border doesn't show up.
I thought the issue might be with this.loading, so I added the scroll check within the observable response, but after loading was set to false. Still no border.
Attempt 2:
<div #textDiv [ngClass]="{'border-class': isScrollable}"> ... </div>
#ViewChild('textDiv') element: ElementRef;
/* ... */
ngAfterViewInit() {
this.isScrollable = this.element.scrollHeight > this.element.clientHeight;
}
But the border still doesn't show up on scrollable content when the page is loaded.
Attempt 3:
The only thing that has worked, is this hot mess:
setTimeout( () => {
this.isScrollable = this.element.scrollHeight > this.element.clientHeight;
});
Is there a way I can get this to work without calling setTimeout?
The problem is here:
<div ngIf="!loading">
<div id="{{someID}}" [ngClass]="{'border-class': isScrollable}"> ...
</div>
The isScrollable is not updating the value after it changes.
You can fix this, using a get and returning the value when ngAfterViewInit was already executed:
export class CustomComponent implements AfterViewInit {
private afterViewInitExecuted = false;
#ViewChild('textDiv') element: ElementRef;
public get isScrollable() {
if(this.afterViewInitExecuted) {
return this.element.scrollHeight > this.element.clientHeight;
}
return false;
}
ngAfterViewInit() {
this.afterViewInitExecuted = true;
}
}
Then in your html:
<div ngIf="!loading">
<div id="{{someID}}" [ngClass]="{'border-class': isScrollable() }"> ...
</div>
With that, it should work.

React: Accessing a target element as 'this'

This has probably been answered before, but I can't seem to google it as it overlaps a bit with .bind(this) questions.
What I want to do is to refer the calling element as this when I run a function e.g.
highlight()
{
this.select();
}
<input value={final_line} onClick={this.highlight} ></input>
However, this is undefined after clicking it. So what would the best way to do this? Right now I'm using event.target as a replacement, which works. I've also seen ref being used, but am not sure if this is applicable as I am returning an array of input.
So my question overall is: Is there an alternative to using event.target?
I agree with GG. - you should use event.target, but an alternative is to use refs:
import { Component } from 'react';
import React from 'react';
class MyComponent extends Component {
render() {
const { final_line } = this.props;
return <input value={final_line}
onClick={ this.highlight.bind(this)}
ref="inputToHighlight"
/>;
}
highlight() {
this.refs.inputToHighlight.select();
}
}
So what would the best way to do this?
There is no way to do this. Using event.target is actually the right way to achieve it.
If you have several inputs, you should use the name property to identify the targeted element:
inputs.map(input =>
<input name={input.name} onClick={this.highlight} />
)
highlight(event) {
this.setState({ [event.target.name]: 'clicked!' })
}
Use call() inside an arrow function as your onClick to set this to event.target like:
onClick={ (event)=>{onClick.call(event.target, contact.id) }

Get React.refs DOM node width after render and trigger a re-render only if width has value has changed

I'm attempting to get the width of a ref DOM element and set state to then use within the Component render. The problem comes because this width changes on user input and when I try setState within componentDidUpdate it starts an infinite loop and my browsers bombs.
I created a fiddle here http://jsbin.com/dizomohaso/1/edit?js,output (open the console for some information)
My thinking was;
Component Mounts, setState: refs.element.clientWidth
User inputs data, triggers render
shouldComponentUpdate returns true only if new.state is not equal to old.state. My problem is, I'm not sure where makes sense to update this state?
Any help will be much appreciated, thanks for reading!
Brad.
var component = React.createClass({
componentDidMount: function() {
//Get initial width. Obviously, this will trigger a render,
//but nothing will change, look wise.
//But, if this is against personal taste then store this property
//in a different way
//But it'll complicate your determineWidth logic a bit.
this.setState({
elWidth: ReactDOM.findDOMNode(this.refs.the_input).getBoundingClientRect().width
})
},
determineWidth: function() {
var elWidth = ReactDOM.findDOMNode(this.refs.the_input).getBoundingClientRect().width
if (this.state.elWidth && this.state.elWidth !== elWidth) {
this.setState({
elWidth: elWidth
})
}
},
render: function() {
var styleProp = {}
if (this.state.elWidth) {
styleProp.style = { width: this.state.elWidth };
}
return (
<input ref="the_input" onChange={this.determineWidth} {...styleProp} />
)
}
})
I like to use .getBoundingClientRect().width because depending on your browser, the element might have a fractional width, and that width will return without any rounding.

DOM element to corresponding vue.js component

How can I find the vue.js component corresponding to a DOM element?
If I have
element = document.getElementById(id);
Is there a vue method equivalent to the jQuery
$(element)
Just by this (in your method in "methods"):
element = this.$el;
:)
The proper way to do with would be to use the v-el directive to give it a reference. Then you can do this.$$[reference].
Update for vue 2
In Vue 2 refs are used for both elements and components: http://vuejs.org/guide/migration.html#v-el-and-v-ref-replaced
In Vue.js 2 Inside a Vue Instance or Component:
Use this.$el to get the HTMLElement the instance/component was mounted to
From an HTMLElement:
Use .__vue__ from the HTMLElement
E.g. var vueInstance = document.getElementById('app').__vue__;
Having a VNode in a variable called vnode you can:
use vnode.elm to get the element that VNode was rendered to
use vnode.context to get the VueComponent instance that VNode's component was declared (this usually returns the parent component, but may surprise you when using slots.
use vnode.componentInstance to get the Actual VueComponent instance that VNode is about
Source, literally: vue/flow/vnode.js.
Runnable Demo:
Vue.config.productionTip = false; // disable developer version warning
console.log('-------------------')
Vue.component('my-component', {
template: `<input>`,
mounted: function() {
console.log('[my-component] is mounted at element:', this.$el);
}
});
Vue.directive('customdirective', {
bind: function (el, binding, vnode) {
console.log('[DIRECTIVE] My Element is:', vnode.elm);
console.log('[DIRECTIVE] My componentInstance is:', vnode.componentInstance);
console.log('[DIRECTIVE] My context is:', vnode.context);
// some properties, such as $el, may take an extra tick to be set, thus you need to...
Vue.nextTick(() => console.log('[DIRECTIVE][AFTER TICK] My context is:', vnode.context.$el))
}
})
new Vue({
el: '#app',
mounted: function() {
console.log('[ROOT] This Vue instance is mounted at element:', this.$el);
console.log('[ROOT] From the element to the Vue instance:', document.getElementById('app').__vue__);
console.log('[ROOT] Vue component instance of my-component:', document.querySelector('input').__vue__);
}
})
<script src="https://unpkg.com/vue#2.5.15/dist/vue.min.js"></script>
<h1>Open the browser's console</h1>
<div id="app">
<my-component v-customdirective=""></my-component>
</div>
If you're starting with a DOM element, check for a __vue__ property on that element. Any Vue View Models (components, VMs created by v-repeat usage) will have this property.
You can use the "Inspect Element" feature in your browsers developer console (at least in Firefox and Chrome) to view the DOM properties.
Hope that helps!
this.$el - points to the root element of the component
this.$refs.<ref name> + <div ref="<ref name>" ... - points to nested element
💡 use $el/$refs only after mounted() step of vue lifecycle
<template>
<div>
root element
<div ref="childElement">child element</div>
</div>
</template>
<script>
export default {
mounted() {
let rootElement = this.$el;
let childElement = this.$refs.childElement;
console.log(rootElement);
console.log(childElement);
}
}
</script>
<style scoped>
</style>
So I figured $0.__vue__ doesn't work very well with HOCs (high order components).
// ListItem.vue
<template>
<vm-product-item/>
<template>
From the template above, if you have ListItem component, that has ProductItem as it's root, and you try $0.__vue__ in console the result unexpectedly would be the ListItem instance.
Here I got a solution to select the lowest level component (ProductItem in this case).
Plugin
// DomNodeToComponent.js
export default {
install: (Vue, options) => {
Vue.mixin({
mounted () {
this.$el.__vueComponent__ = this
},
})
},
}
Install
import DomNodeToComponent from'./plugins/DomNodeToComponent/DomNodeToComponent'
Vue.use(DomNodeToComponent)
Use
In browser console click on dom element.
Type $0.__vueComponent__.
Do whatever you want with component. Access data. Do changes. Run exposed methods from e2e.
Bonus feature
If you want more, you can just use $0.__vue__.$parent. Meaning if 3 components share the same dom node, you'll have to write $0.__vue__.$parent.$parent to get the main component. This approach is less laconic, but gives better control.
Since v-ref is no longer a directive, but a special attribute, it can also be dynamically defined. This is especially useful in combination with v-for.
For example:
<ul>
<li v-for="(item, key) in items" v-on:click="play(item,$event)">
<a v-bind:ref="'key' + item.id" v-bind:href="item.url">
<!-- content -->
</a>
</li>
</ul>
and in Vue component you can use
var recordingModel = new Vue({
el:'#rec-container',
data:{
items:[]
},
methods:{
play:function(item,e){
// it contains the bound reference
console.log(this.$refs['key'+item.id]);
}
}
});
I found this snippet here. The idea is to go up the DOM node hierarchy until a __vue__ property is found.
function getVueFromElement(el) {
while (el) {
if (el.__vue__) {
return el.__vue__
} else {
el = el.parentNode
}
}
}
In Chrome:
Solution for Vue 3
I needed to create a navbar and collapse the menu item when clicked outside. I created a click listener on windows in mounted life cycle hook as follows
mounted() {
window.addEventListener('click', (e)=>{
if(e.target !== this.$el)
this.showChild = false;
})
}
You can also check if the element is child of this.$el. However, in my case the children were all links and this didn't matter much.
If you want listen an event (i.e OnClick) on an input with "demo" id, you can use:
new Vue({
el: '#demo',
data: {
n: 0
},
methods: {
onClick: function (e) {
console.log(e.target.tagName) // "A"
console.log(e.targetVM === this) // true
}
}
})
Exactly what Kamil said,
element = this.$el
But make sure you don't have fragment instances.
Since in Vue 2.0, no solution seems available, a clean solution that I found is to create a vue-id attribute, and also set it on the template. Then on created and beforeDestroy lifecycle these instances are updated on the global object.
Basically:
created: function() {
this._id = generateUid();
globalRepo[this._id] = this;
},
beforeDestroy: function() {
delete globalRepo[this._id]
},
data: function() {
return {
vueId: this._id
}
}

Apply background-color in ckeditor textarea

I'm having some problems to apply a background-color in the textarea of a ckeditor instance.
When the user clicks on submit without adding any text, it's shown a message telling him to fill all the required fields, and these required fields areas all with the text-fields set with background-color: #CFC183;.
As the ckeditor is created with javascript code, I was using it to try to check if there's any text entered in the text area. if there's no character, I apply the changes.
When I apply in the console this code:
CKEDITOR.instances.body.document.getBody().setStyle('background-color', '#CFC183');
It applies the background exactly like I want to.
So, I added this javascript code in my javascript file to try to manage it, but doesn't seems to be working. Here's my code:
var editorInstance = CKEDITOR.replace('body', { toolbar : 'Full' });
editorInstance.on("instanceReady", function (ev) {
var editorCKE = CKEDITOR.instances.body; readyMap[editorCKE] = true;
editorCKE.setReadOnly(true);
});
var hasText = CKEDITOR.instances.body.document.getBody().getChild(0).getText();
if (!hasText) {
CKEDITOR.on('instanceCreated', function(e) {
e.editor.document.getBody().setStyle('background-color', '#CFC183');
});
}
Firebug shows this error message:
TypeError: CKEDITOR.instances.body.document is undefined
I'm not that good at Javascript, so is there anything wrong with my code?
I already checked this question here, so I believe there's something wrong with my javascript code and I want your help, please.
I guess that you've got an error in this line:
var hasText = CKEDITOR.instances.body.document.getBody().getChild(0).getText();
This is because you're trying to get document element before it's ready (before instanceReady event).
The same error will be thrown here:
if (!hasText) {
CKEDITOR.on('instanceCreated', function(e) {
e.editor.document.getBody().setStyle('background-color', '#CFC183');
});
}
Again - instanceCreated is still too early. You have to move all that code to instanceReady listener. You'll have something like (I'm not sure if I understand what you're trying to achieve):
var editor = CKEDITOR.replace( 'body', { toolbar: 'Full' } );
editor.on( 'instanceReady', function( evt ) {
readyMap[ editor.name ] = true;
editor.setReadOnly( true );
var hasText = editor.document.getBody().getFirst().getText();
if ( !hasText ) {
editor.document.getBody().setStyle( 'background-color', '#CFC183' );
}
} );
As you can see, there is one more issue in your code:
readyMap[editorCKE] = true;
In JS there are no weak maps (yet, but they will be introduced soon). Only strings can be used as a keys of an object. In your case toString() method will be called on editorCKE, which returns [object Object]. That's why I added name property there.

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