Develop Reference

Reset Render on page reload UseEffect and Css

Im starting with react and im trying to make a horizontal scrolling page. It seems to work just fine except for one thing, of which i'm pretty certain i'm missing some React logic for this.
I use a targetContainer div with in it, several pages (fullscreen) and a Navbuttons class to move it around.
In my code below i use a 'NavButtons' functional component that sets the targetContainers 'left' value.
But when I reload the page with F5, my page stays on set style (e.g. left:-300%) but pageCounter goes back to 0, breaking the nav buttons...
I'm pretty certain its because i'm using the css-style but what's the right/best way to solve this?
import React, { useEffect, useState } from 'react';
const NavButtons = (props) => {
const maxCount = props.maxCount;
const [pageCounter, setPageCounter] = useState(0);
const scrollPrev = function () {
if (pageCounter > 0) {
setPageCounter(pageCounter - 1);
}
}
const scrollNext = function () {
if (pageCounter < (maxCount - 1)) {
setPageCounter(pageCounter + 1);
}
}
useEffect(() => {
props.targetContainer.current.style.left = -((pageCounter) * 100) + 'vw';
}, [pageCounter, props.targetContainer]);
useEffect(() => {
setToZero();
}, []);
const setToZero = function () {
setPageCounter(0);
props.targetContainer.current.style.left = 0;
}
return (
<div className="NavButtons">
<button onClick={scrollPrev}>Prev</button>
<button onClick={scrollNext}>Next</button>
</div>
)
}
export default NavButtons;
Here is a stackblitz,
https://react-zyvu7o.stackblitz.io/
Edit on:
https://stackblitz.com/edit/react-zyvu7o?file=src/components/Navbuttons.js
It 'unfortunately' works normal on stackblits, but not on my localhost... :(

I'm fairly confident this only occurs due to browser caching & hot reloading, which is why it's working in your example and not locally.

How can I conditionally show title tooltip if CSS ellipsis is active within a React component

Problem:
I'm looking for a clean way to show a title tooltip on items that have a CSS ellipsis applied. (Within a React component)
What I've tried:
I setup a ref, but it doesn't exist until componentDidUpdate, so within componentDidUpdate I forceUpdate. (This needs some more rework to handle prop changes and such and I would probably use setState instead.) This kind of works but there are a lot of caveats that I feel are unacceptable.
setState/forceUpdate - Maybe this is a necessary evil
What if the browser size changes? Do I need to re-render with every resize? I suppose I'd need a debounce on that as well. Yuck.
Question:
Is there a more graceful way to accomplish this goal?
Semi-functional MCVE:
https://codepen.io/anon/pen/mjYzMM
class App extends React.Component {
render() {
return (
<div>
<Test message="Overflow Ellipsis" />
<Test message="Fits" />
</div>
);
}
}
class Test extends React.Component {
constructor(props) {
super(props);
this.element = React.createRef();
}
componentDidMount() {
this.forceUpdate();
}
doesTextFit = () => {
if (!this.element) return false;
if (!this.element.current) return false;
console.log(
"***",
"offsetWidth: ",
this.element.current.offsetWidth,
"scrollWidth:",
this.element.current.scrollWidth,
"doesTextFit?",
this.element.current.scrollWidth <= this.element.current.offsetWidth
);
return this.element.current.scrollWidth <= this.element.current.offsetWidth;
};
render() {
return (
<p
className="collapse"
ref={this.element}
title={this.doesTextFit() ? "it fits!" : "overflow"}
>
{this.props.message}
</p>
);
}
}
ReactDOM.render(<App />, document.getElementById("container"));
.collapse {
width:60px;
white-space: nowrap;
overflow: hidden;
text-overflow: ellipsis;
}
<script crossorigin src="https://unpkg.com/react#16/umd/react.production.min.js"></script>
<script crossorigin src="https://unpkg.com/react-dom#16/umd/react-dom.production.min.js"></script>
<div id="container"></div>

Since a lot of people are still viewing this question. I did finally figure out how to do it. I'll try to rewrite this into a working example at some point but here's the gist.
// Setup a ref
const labelRef = useRef(null);
// State for tracking if ellipsis is active
const [isEllipsisActive, setIsEllipsisActive] = useState(false);
// Setup a use effect
useEffect(() => {
if(labelRef?.current?.offsetWidth < labelRef?.current?.scrollWidth) {
setIsEllipsisActive(true);
}
}, [labelRef?.current, value, isLoading]); // I was also tracking if the data was loading
// Div you want to check if ellipsis is active
<div ref={labelRef}>{value}</div>

I use this framework agnostic snippet to this. Just include it on your page and see the magic happen ;)
(function() {
let lastMouseOverElement = null;
document.addEventListener("mouseover", function(event) {
let element = event.target;
if (element instanceof Element && element != lastMouseOverElement) {
lastMouseOverElement = element;
const style = window.getComputedStyle(element);
const whiteSpace = style.getPropertyValue("white-space");
const textOverflow = style.getPropertyValue("text-overflow");
if (whiteSpace == "nowrap" && textOverflow == "ellipsis" && element.offsetWidth < element.scrollWidth) {
element.setAttribute("title", element.textContent);
} else {
element.removeAttribute("title");
}
}
});
})();
From:
https://gist.github.com/JoackimPennerup/06592b655402d1d6181af32def40189d

Angular 4 | window.scrollTo(); is not working properly

Currently, I'm trying to automatically scroll to the top of the HTML page for which I'm using in my Typescript.
window.scrollTo(0 , 0);
and while trying to automatically scroll down to bottom of the HTML page
window.scrollTo( 0 , document.body.scrollHeight);
I'm trying to scroll top after an HTTP response.
Code
openPDFVievwer(data) {
this.obj= JSON.parse(data._body);
document.getElementById('spinner').style.display = 'none';
window.scrollTo( 0 , 0);
}
when I'm trying to scroll bottom after rendering another component.
Code
searchData(data) {
this.document = data;
this.searchResultDiv = true; // where component will be rendered
window.scrollTo( 0 , document.body.scrollHeight);
}
but, both seem to be not working.
Is there something that I'm doing wrong?

try into html
<div #list [scrollTop]="list.scrollHeight"></div>
Solution 2
In Component
define id into html id="scrollId"
const element = document.querySelector('#scrollId');
element.scrollIntoView();

Answer for angular 2+
It's very simple,
Just create an any element
e.g.
<span id="moveTop"></span> or add just id into the element or use already existed Id where you have to move top, down, mid etc.
and add this method on specific event, like I want to move top when edit as my list list too much.
gotoTop() {
var scrollElem= document.querySelector('#moveTop');
scrollElem.scrollIntoView();
}
or If you want to send Id as Parameter you simply just create Optional Parameter
gotoTop(elementId?: string) {
if (elementId != null) {
var element = document.querySelector(elementId);
element.scrollIntoView();
}
else {
var element = document.querySelector('#moveTop');
element.scrollIntoView();
}
}

Above solution wasn't working for me, Try this
code:
import { Router, NavigationEnd } from '#angular/router';
constructor(private router: Router)
ngOnInit()
{
this.router.events.subscribe((evt) => {
if (!(evt instanceof NavigationEnd)) {
return;
}
document.getElementsByTagName("app-website-nav")[0].scrollIntoView();
});
}

Scroll to bottom of div with Vue.js

I have a Vue.js component with several elements in it. I want to automatically scroll to the bottom of that element when a method in the component is called.
Basically, do the same as this. However, I haven't found a way to get the element within my component and modify scrollTop
I'm currently using Vue.js 2.0.8.

2022 easy, readable, smooth scrolling ability, & won't hurt your brain... use el.scrollIntoView()
scrollIntoView() has options you can pass it like scrollIntoView({behavior: 'smooth'}) to get smooth scrolling out of the box and does not require any external libraries.
Here is a fiddle.
methods: {
scrollToElement() {
const el = this.$refs.scrollToMe;
if (el) {
// Use el.scrollIntoView() to instantly scroll to the element
el.scrollIntoView({behavior: 'smooth'});
}
}
}
Then if you wanted to scroll to this element on page load you could call this method like this:
mounted() {
this.scrollToElement();
}
Else if you wanted to scroll to it on a button click or some other action you could call it the same way:
<button #click="scrollToElement">scroll to me</button>
The scroll works all the way down to IE 8. The smooth scroll effect does not work out of the box in IE or Safari. If needed there is a polyfill available for this here as #mostafaznv mentioned in the comments.

As I understand, the desired effect you want is to scroll to the end of a list (or scrollable div) when something happens (e.g.: an item is added to the list). If so, you can scroll to the end of a container element (or even the page it self) using only pure JavaScript and the VueJS selectors.
var container = this.$el.querySelector("#container");
container.scrollTop = container.scrollHeight;
I've provided a working example in this fiddle.
Every time a item is added to the list, the list is scrolled to the end to show the new item.

I tried the accepted solution and it didn't work for me. I use the browser debugger and found out the actual height that should be used is the clientHeight BUT you have to put this into the updated() hook for the whole solution to work.
data(){
return {
conversation: [
{
}
]
},
mounted(){
EventBus.$on('msg-ctr--push-msg-in-conversation', textMsg => {
this.conversation.push(textMsg)
// Didn't work doing scroll here
})
},
updated(){ <=== PUT IT HERE !!
var elem = this.$el
elem.scrollTop = elem.clientHeight;
},

Use the ref attribute on the DOM element for reference
<div class="content scrollable" ref="msgContainer">
<!-- content -->
</div>
You need to setup a WATCH
data() {
return {
count: 5
};
},
watch: {
count: function() {
this.$nextTick(function() {
var container = this.$refs.msgContainer;
container.scrollTop = container.scrollHeight + 120;
});
}
}
Ensure you're using proper CSS
.scrollable {
overflow: hidden;
overflow-y: scroll;
height: calc(100vh - 20px);
}

Here is a simple example using ref to scroll to the bottom of a div.
/*
Defined somewhere:
var vueContent = new Vue({
el: '#vue-content',
...
*/
var messageDisplay = vueContent.$refs.messageDisplay;
messageDisplay.scrollTop = messageDisplay.scrollHeight;
<div id='vue-content'>
<div ref='messageDisplay' id='messages'>
<div v-for="message in messages">
{{ message }}
</div>
</div>
</div>
Notice that by putting ref='messageDisplay' in the HTML, you have access to the element through vueContent.$refs.messageDisplay

If you need to support IE11 and (old) Edge, you can use:
scrollToBottom() {
let element = document.getElementById("yourID");
element.scrollIntoView(false);
}
If you don't need to support IE11, the following will work (clearer code):
scrollToBottom() {
let element = document.getElementById("yourID");
element.scrollIntoView({behavior: "smooth", block: "end"});
}

Try vue-chat-scroll:
Install via npm: npm install --save vue-chat-scroll
Import:
import Vue from 'vue'
import VueChatScroll from 'vue-chat-scroll'
Vue.use(VueChatScroll)
in app.js after window.Vue = require('vue').default;
then use it with :
<ul class="messages" v-chat-scroll>
// your message/chat code...
</ul>

For those that haven't found a working solution above, I believe I have a working one. My specific use case was that I wanted to scroll to the bottom of a specific div - in my case a chatbox - whenever a new message was added to the array.
const container = this.$el.querySelector('#messagesCardContent');
this.$nextTick(() => {
// DOM updated
container.scrollTop = container.scrollHeight;
});
I have to use nextTick as we need to wait for the dom to update from the data change before doing the scroll!
I just put the above code in a watcher for the messages array, like so:
messages: {
handler() {
// this scrolls the messages to the bottom on loading data
const container = this.$el.querySelector('#messagesCard');
this.$nextTick(() => {
// DOM updated
container.scrollTop = container.scrollHeight;
});
},
deep: true,
},

The solution did not work for me but the following code works for me. I am working on dynamic items with class of message-box.
scrollToEnd() {
setTimeout(() => {
this.$el
.getElementsByClassName("message-box")
[
this.$el.getElementsByClassName("message-box").length -
1
].scrollIntoView();
}, 50);
}
Remember to put the method in mounted() not created() and add class message-box to the dynamic item. setTimeout() is essential for this to work. You can refer to https://forum.vuejs.org/t/getelementsbyclassname-and-htmlcollection-within-a-watcher/26478 for more information about this.

This is what worked for me
this.$nextTick(() => {
let scrollHeight = this.$refs.messages.scrollHeight
window.scrollTo(0, scrollHeight)
})

In the related question you posted, we already have a way to achieve that in plain javascript, so we only need to get the js reference to the dom node we want to scroll.
The ref attribute can be used to declare reference to html elements to make them available in vue's component methods.
Or, if the method in the component is a handler for some UI event, and the target is related to the div you want to scroll in space, you can simply pass in the event object along with your wanted arguments, and do the scroll like scroll(event.target.nextSibling).

I had the same need in my app (with complex nested components structure) and I unfortunately did not succeed to make it work.
Finally I used vue-scrollto that works fine !

My solutions without modules:
Template
<div class="scrollable-content" ref="conversations" />
Script
scrollToBottom() {
const container = this.$refs.conversations;
container.scrollTop = container.scrollHeight;
},

scrollToBottom() {
this.$nextTick(function () {
let BoxEl = document.querySelector('#Box');
if(BoxEl)
BoxEl.scrollTop = BoxEl.scrollHeight;
});
}

Agree with Lurein Perera
Just want to add extra info
watch: {
arrayName: {
handler() {
const container = this.$el.querySelector("#idName");
this.$nextTick(() => {
container.scrollTop = container.scrollHeight;
});
},
deep: true,
},
},
Where as:
arrayName = Name of array
idName = The id attribute has to be added to the div where you want the scrollbar to auto-scroll down when arrayName length increases.

scrollToElement() {
const element = this.$refs.abc; // here abc is the ref of the element
if (element) {
el.scrollIntoView({behavior: 'smooth'});
}
}
}
here you need to use ref for the particular div or element which you want make visible on scroll.
if you have a table and you want to locate the last row of the table then you have to use -
element.lastElementChild.scrollIntoView({behaviour:'smooth'})
Here not that if you ware asynchronously adding the element to the table then you have to take care of it. you can test it using setTimeout, if that is making any difference.
e.g.
const element = this.$refs.abc;
if (element) {
setTimeout(() => {
element.lastElementChild.scrollIntoView({behaviour:'smooth'})
}, 1000);
}
}
replace set timeout with your own async logic.

Using Composition API and TypeScript
I set the parameter scrollTop equal to scrollHeightfrom the HTMLDivElment API.
<template>
<div id="container" ref="comments">
Content ...
</div>
</template>
<script lang="ts">
import { defineComponent, ref, Ref, watchEffect } from 'vue'
export default defineComponent({
setup() {
const comments: Ref<null | HTMLDivElement> = ref(null)
watchEffect(() => {
if(comments.value) {
comments.value.scrollTop = comments.value.scrollHeight
}
})
return {
comments
}
}
})
</script>

Get div's offsetTop positions in React

I am trying to implement a List view in React.
What I am trying to achieve is that to store the list headers informations and register the components and register the scroll event.
every time when user scroll the window, I'd like to take out the stored div and re-calculate the offsetTop data.
The problem now is that, I found the console just print out the initial value (the value is fixed and never changed) offsetTop data never change in onscroll function.
Anyone suggest how to get latest offsetTop from the _instances object?
import React, { Component } from 'react';
import ListHeader from './lib/ListHeader';
import ListItems from './lib/ListItems';
const styles = {
'height': '400px',
'overflowY': 'auto',
'outline': '1px dashed red',
'width': '40%'
};
class HeaderPosInfo {
constructor(headerObj, originalPosition, originalHeight) {
this.headerObj = headerObj;
this.originalPosition = originalPosition;
this.originalHeight = originalHeight;
}
}
export default class ReactListView extends Component {
static defaultProps = {
events: ['scroll', 'mousewheel', 'DOMMouseScroll', 'MozMousePixelScroll', 'resize', 'touchmove', 'touchend'],
_instances:[],
_positionMap: new Set(),
_topPos:'',
_topWrapper:''
}
static propTypes = {
data: React.PropTypes.array.isRequired,
headerAttName: React.PropTypes.string.isRequired,
itemsAttName: React.PropTypes.string.isRequired,
events: React.PropTypes.array,
_instances: React.PropTypes.array,
_positionMap: React.PropTypes.object,
_topPos: React.PropTypes.string,
_topWrapper: React.PropTypes.object
};
state = {
events: this.props.events,
_instances: this.props._instances,
_positionMap: this.props._positionMap,
_topPos: this.props._topPos
}
componentDidMount() {
this.initStickyHeaders();
}
componentWillUnmount() {
}
componentDidUpdate() {
}
refsToArray(ctx, prefix){
let results = [];
for (let i=0;;i++){
let ref = ctx.refs[prefix + '-' + String(i)];
if (ref) results.push(ref);
else return results;
}
}
initHeaderPositions() {
// Retrieve all instance of headers and store position info
this.props._instances.forEach((k)=>{
this.props._positionMap.add(new HeaderPosInfo(
k,
k.refs.header.getDOMNode().offsetTop,
k.refs.header.getDOMNode().offsetHeight
));
});
let it = this.props._positionMap.values();
let first = it.next();
this.props._topPos = first.value.originalPosition;
this.props._topWrapper = first.value.headerObj;
}
initStickyHeaders () {
this.props._instances = this.refsToArray(this, 'ListHeader');
this.initHeaderPositions();
// Register events listeners with the listview div
this.props.events.forEach(type => {
if (window.addEventListener) {
React.findDOMNode(this.refs.listview).addEventListener(type, this.onScroll.bind(this), false);
} else {
React.findDOMNode(this.refs.listview).attachEvent('on' + type, this.onScroll.bind(this), false);
}
});
}
onScroll() {
// update current header positions and apply fixed positions to the top one
console.log(1);
let offsetTop = React.findDOMNode(this.props._instances[0].refs.header).offsetTop;
}
render() {
const { data, headerAttName, itemsAttName } = this.props;
let _refi = 0;
let makeRef = () => {
return 'ListHeader-' + (_refi++);
};
return (
<div ref="listview" style={styles}>
{
Object.keys(data).map(k => {
const header = data[k][headerAttName];
const items = data[k][itemsAttName];
return (
<ul key={k}>
<ListHeader ref={makeRef()} header={header} />
<ListItems items={items} />
</ul>
);
})
}
</div>
);
}
}
The whole source code is on Github, you can clone and compile it from here:
Github

You may be encouraged to use the Element.getBoundingClientRect() method to get the top offset of your element. This method provides the full offset values (left, top, right, bottom, width, height) of your element in the viewport.
Check the John Resig's post describing how helpful this method is.

I do realize that the author asks question in relation to a class-based component, however I think it's worth mentioning that as of React 16.8.0 (February 6, 2019) you can take advantage of hooks in function-based components.
Example code:
import { useRef } from 'react'
function Component() {
const inputRef = useRef()
return (
<input ref={inputRef} />
<div
onScroll={() => {
const { offsetTop } = inputRef.current
...
}}
>
)
}

Eugene's answer uses the correct function to get the data, but for posterity I'd like to spell out exactly how to use it in React v0.14+ (according to this answer):
import ReactDOM from 'react-dom';
//...
componentDidMount() {
var rect = ReactDOM.findDOMNode(this)
.getBoundingClientRect()
}
Is working for me perfectly, and I'm using the data to scroll to the top of the new component that just mounted.

A quicker way if you are using React 16.3 and above is by creating a ref in the constructor, then attaching it to the component you wish to use with as shown below.
...
constructor(props){
...
//create a ref
this.someRefName = React.createRef();
}
onScroll(){
let offsetTop = this.someRefName.current.offsetTop;
}
render(){
...
<Component ref={this.someRefName} />
}

import ReactDOM from 'react-dom';
//...
componentDidMount() {
var n = ReactDOM.findDOMNode(this);
console.log(n.offsetTop);
}
You can just grab the offsetTop from the Node.

A better solution with ref to avoid findDOMNode that is discouraged.
...
onScroll() {
let offsetTop = this.instance.getBoundingClientRect().top;
}
...
render() {
...
<Component ref={(el) => this.instance = el } />
...

onScroll has a events whict contains all the native and child elements inside this div so u can use it like this shown below and get the targetted element offsetTop.
const getoffSet = e => {
console.log(e, e.natiiveEvent.target.childNodes[0].offsetTop)
}
return (
<div onScroll={(e) => getoffSet(e)} ref={listview} style={styles}>
</div>
)

Checking if height Property Is Not Set on Parent:
If the parent element has no height set then the sticky element won't
have any area to stick to when scrolling. This happens because the
sticky element is meant to stick/scroll within the height of a
container.
Checking if a Parent Element Is a Flexbox
If sticky element's parent is a flexbox, there are two scenarios to
check for:
The sticky element has align-self: auto set (which is the default);
The sticky element has align-self: stretch set. If the Sticky Element
Has align-self: auto Set: In this case the value of align-self would
compute to the parent's align-items value. So,
if the parent has align-items: normal (which is the default) or
align-items: stretch set, then it means the height of the sticky element would stretch to fill the entire available space. This would leave no room for the sticky element to scroll within the parent.
If the Sticky Element Has align-self: stretch Set:
In this case, the sticky element would stretch to the height of the parent, and would not have any area to scroll within.
How to Make Sticky Element Scrollable Within a Flexbox:
You could simply set the value of the align-self property to align-self: flex-start. This would put the sticky element at the start and won't stretch it.enter link description here