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React modal scroll to top

I have a modal with a long form in my react application. So when I submit the form I am showing the validation messages from the server on top of the form. So the user has to scroll to the top to view the messages. So I want to automatically scroll to the top when the message appears. So I added the below code in the submit handler function. But it is not working.
setAddModalErrorMsg([{ msg: res.data.msg, type: "error" }])
window.scrollTo({
top: 0,
left: 0,
behavior: "smooth"
});

The other answers showed how you can scroll the modal to the top, and that is the generally accepted way of achieving this, though, I want to show you how to scroll the "Message" into view, regardless of whether it's on the top or not.
You would also need to create a ref to where you display your message and use the scrollIntoView functionality to scroll the modal to your validation message.
import React, { useRef } from 'react';
const Modal = () => {
const validationMessageRef = useRef();
const setAddModalErrorMsg = () => {
// scrolls the validation message into view, and the block: 'nearest' ensures it scrolls the modal and not the window
validationMessageRef.current?.scrollIntoView({ block:'nearest' });
}
return (
<div>
<div ref={validationMessageRef}>
// your validation message is displayed here
</div>
// rest of your modal content here
</div>
)
}

to automatically scroll to the top we can use the below code :
constructor(props) {
super(props)
this.myRef = React.createRef() // Create a ref object
}
add the scrollTo function after setAddModalErrorMsg.
setAddModalErrorMsg([{ msg: res.data.msg, type: "error" }])
this.myRef.current.scrollTo(0, 0);
<div ref={this.myRef}></div>
attach the ref property to a top dom element

You're trying to scroll window, but chances are your window is already at the top, it's your modal element that needs to scroll up.
To do this, i'd create a reference to the modal element, then in your function scroll the modal element via the ref, so something along the lines of:
import React, {useRef} from 'react';
const Modal = (props) => {
// use the useRef hook to store a reference to the element
const modalRef = useRef();
const setAddModalErrorMsg = () => {
// check the ref exists (it should always exist, it's declared in the JSX below), and call a regular javascript scrollTo function on it
modalRef.current?.scrollTo({x: 0, y: 0, animated: false});
}
// see here we create a reference to the div that needs scrolled
return (
<div ref={modalRef}>
{ // your modal content }
</div>
)
}

page back button not resetting css

I have a button that "navigates" to a new page.
To do this the button makes the current section's/page's display settings = none and the new section/page's display = block.
<div class="listLeft"><p class="listItems" onclick="navButtons('work')">work</p><p class="listItems" onclick="navButtons('about')">about</p></div>
<div class="listRight"><p class="listItems" onclick="navButtons('playground')">playground</p><p class="listItems" onclick="navButtons('contact')">contact</p></div>
js below
function navButtons(page) {
let section = document.getElementById(page);
section.setAttribute("class", "visible");
window.location.href = `#${page}page`;
window.scrollTo(0, document.body.scrollHeight);
let pagesArrayCopy = [...pagesArray]
const unselected = pagesArrayCopy.filter(item => item.id !== page);
setTimeout(() => {
unselected.forEach((el, index) => unselected[index].setAttribute("class", "invisible"));
pagesArray = Array.from(pagesNodeList);
}, 500);
};
when I press the back button the url is obviously changing back to the old #section, but the css doesn't reset, so the new page is still visible and the previous page is still display = none.
How do i get around this, so when the back button is pressed the css values reset to default?

Try to use an anchor tag so your URL actually change (ie: update the adress to mypage.html#page2).
Then you could bind a function to onhashchange and check of your page is well displayed.

you haven't supplied all the html. there's no id work so section is null
function navButtons(page) {
let section = document.getElementById(page);
console.log(section)
section.setAttribute("class", "visible");
window.location.href = `#${page}page`;
window.scrollTo(0, document.body.scrollHeight);
let pagesArrayCopy = [...pagesArray]
const unselected = pagesArrayCopy.filter(item => item.id !== page);
setTimeout(() => {
unselected.forEach((el, index) => unselected[index].setAttribute("class", "invisible"));
pagesArray = Array.from(pagesNodeList);
}, 500);
};
<div class="listLeft">
<p class="listItems" onclick="navButtons('work')">work</p>
<p class="listItems" onclick="navButtons('about')">about</p></div>
<div class="listRight">
<p class="listItems" onclick="navButtons('playground')">playground</p>
<p class="listItems" onclick="navButtons('contact')">contact</p></div>

Another way to do this is to bind your changing state to the history of the browser. Since there is no real way of overriding the 'back' button on the browser, you will have to write it into your history. See the History API for HTML5 here:
https://css-tricks.com/using-the-html5-history-api/
The same thing specified above can also be done with this plugin:
https://code.google.com/archive/p/reallysimplehistory/

Remain at the same vertical coordinate when loading more data in Vue.js

I have a load more button which loads more data to a component. However, after pressing the load button the user is scrolled at the bottom of screen since the load more button is also located at the bottom of the screen.
The user has to scroll up to see the loaded content. Is there any way to make the user to remain at the same vertical coordinate when pressing the button?

One solution if you like to scroll to original position where the Load More button locates:
uses ref to mark the related VNodes (scrolling Container ref=container and the anchor ref=test)
when Load Button is pressed, get current button position
After new content is loaded, call scrollTo method to scroll to the position it got in Step 2 inside nextTick callback
new Vue ({
el:'#app',
data () {
return {
rows: Array.from({length: 100}).map((_, index) => index),
current: 5,
currentCoords: {top: 0, left: 0}
}
},
computed: {
computedRows: function () {
return this.rows.slice(0, this.current)
}
},
methods: {
loadMore: function () {
this.currentCoords.top = this.$refs.test.offsetTop
this.currentCoords.left = this.$refs.test.offsetLeft
this.current += 15
this.$nextTick(() => {
this.$refs.container.scrollTo(this.currentCoords.left, this.currentCoords.top - 10)
})
}
}
})
<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.16/vue.js"></script>
<div id="app">
<div class="container">
<div ref="container" style="max-height: 200px;overflow:auto">
<p v-for="(row, index) in computedRows" :key="index">{{row}}</p>
<button ref="test" #click="loadMore()">Load More</button>
</div>
</div>
</div>

JavaScript classes, how does one apply "Separation of Concerns" and "Don't repeat Yourself" (DRY) in practice

I'm just in the process of learning how JavaScript classes work and I'm just looking for some advice on how to achieve something quite simple I hope regarding animating some elements.
I have created a class named myAnimation, the constructor takes in 1 argument which is an element. All its doing is fading a heading out and in, all very simple. It works fine when there is just one heading element on the page, I'm just not to sure how I go about getting it to work with more than one heading.
Please excuse my naivety with this; it's all very new to me, this is just a basic example I have managed to make myself to try and help myself understand how it works.
class myAnimation {
constructor(element) {
this.element = document.querySelector(element);
}
fadeOut(time) {
if (this.element.classList.contains('fadeout-active')) {
this.element.style.opacity = 1;
this.element.classList.remove('fadeout-active');
button.textContent = 'Hide Heading';
} else {
this.element.style.opacity = 0;
this.element.style.transition = `all ${time}s ease`;
this.element.classList.add('fadeout-active');
button.textContent = 'Show Heading';
}
}
}
const heading = new myAnimation('.heading');
const button = document.querySelector('.button');
button.addEventListener('click', () => {
heading.fadeOut(1);
});
<div class="intro">
<h1 class="heading">Intro Heading</h1>
<p>This is the intro section</p>
<button class="button">Hide Heading</button>
</div>
<div class="main">
<h1 class="heading">Main Heading</h1>
<p>This is the main section</p>
<button class="button">Hide Heading</button>
</div>

After my comment I wanted to make the script run in a way I thought it might have been intended by the OP.
Even though it demonstrates what needs to be done in order to run properly, the entire base design proofs to be not fitting to what the OP really might need to achieve.
The class is called Animation but from the beginning it was intermingling element-animation and changing state of a single somehow globally scoped button.
Even though running now, the design does not proof to be a real fit because one now passes the element that is going to be animated and the button it shall interact with altogether into the constructor.
The functionality is grouped correctly, just the place and the naming doesn't really fit.
The OP might think about a next iteration step of the provided code ...
class Animation {
constructor(elementNode, buttonNode) {
this.element = elementNode;
this.button = buttonNode;
// only in case both elements were passed ...
if (elementNode && buttonNode) {
// couple them by event listening/handling.
buttonNode.addEventListener('click', () => {
// - accessing the `Animation` instance's `this` context
// gets assured by making use of an arrow function.
this.fadeOut(1);
});
}
}
fadeOut(time) {
if (this.element.classList.contains('fadeout-active')) {
this.element.style.opacity = 1;
this.element.classList.remove('fadeout-active');
this.button.textContent = 'Hide Heading';
} else {
this.element.style.opacity = 0;
this.element.style.transition = `all ${time}s ease`;
this.element.classList.add('fadeout-active');
this.button.textContent = 'Show Heading';
}
}
}
function initializeAnimations() {
// get list of all elements that have a `heading` class name.
const headingList = document.querySelectorAll('.heading');
// for each heading element do ...
headingList.forEach(function (headingNode) {
// ... access its parent element and query again for a single button.
const buttonNode = headingNode.parentElement.querySelector('.button');
// if the related button element exists ...
if (buttonNode) {
// ... create a new `Animation` instance.
new Animation(headingNode, buttonNode);
}
});
}
initializeAnimations();
.as-console-wrapper { max-height: 100%!important; top: 0; }
<div class="intro">
<h1 class="heading">Intro Heading</h1>
<p>This is the intro section</p>
<button class="button">Hide Heading</button>
</div>
<div class="main">
<h1 class="heading">Main Heading</h1>
<p>This is the main section</p>
<button class="button">Hide Heading</button>
</div>
... new day, next possible iteration step ...
The 2nd iteration separates concerns.
It does so by renaming the class and implementing only class specific behavior. Thus a FadeToggle class provides just toggle specific functionality.
The code then gets split into two functions that handle initialization. For better reuse the initializing code and the html structure need to be refactored into something more generic. The data attribute of each container that features a trigger-element for fading a target element will be used as a configuration storage that provides all necessary information for the initializing process. (One even can provide individual transition duration values.)
Last there is a handler function that is implemented in a way that it can be reused by bind in order to generate a closure which provides all the necessary data for each trigger-target couple.
class FadeToggle {
// a clean fade-toggle implementation.
constructor(elementNode, duration) {
duration = parseFloat(duration, 10);
duration = Number.isFinite(duration) ? duration : 1;
elementNode.style.opacity = 1;
elementNode.style.transition = `all ${ duration }s ease`;
this.element = elementNode;
}
isFadeoutActive() {
return this.element.classList.contains('fadeout-active');
}
toggleFade(duration) {
duration = parseFloat(duration, 10);
if (Number.isFinite(duration)) {
this.element.style.transitionDuration = `${ duration }s`;
}
if (this.isFadeoutActive()) {
this.element.style.opacity = 1;
this.element.classList.remove('fadeout-active');
} else {
this.element.style.opacity = 0;
this.element.classList.add('fadeout-active');
}
}
}
function handleFadeToggleWithBoundContext(/* evt */) {
const { trigger, target } = this;
if (target.isFadeoutActive()) {
trigger.textContent = 'Hide Heading';
} else {
trigger.textContent = 'Show Heading';
}
target.toggleFade();
}
function initializeFadeToggle(elmNode) {
// parse an element node's fade-toggle configuration.
const config = JSON.parse(elmNode.dataset.fadeToggleConfig || null);
const selectors = (config && config.selectors);
if (selectors) {
try {
// query both the triggering and the target element
const trigger = elmNode.querySelector(selectors.trigger || null);
let target = elmNode.querySelector(selectors.target || null);
if (trigger && target) {
// create a `FadeToggle` target type.
target = new FadeToggle(target, config.duration);
// couple trigger and target by event listening/handling ...
trigger.addEventListener(
'click',
handleFadeToggleWithBoundContext.bind({
// ... and binding both as context properties to the handler.
trigger,
target
})
);
}
} catch (exception) {
console.warn(exception.message, exception);
}
}
}
function initializeEveryFadeToggle() {
// get list of all elements that contain a fade-toggle configuration
const configContainerList = document.querySelectorAll('[data-fade-toggle-config]');
// do initialization for each container separately.
configContainerList.forEach(initializeFadeToggle);
}
initializeEveryFadeToggle();
.as-console-wrapper { max-height: 100%!important; top: 0; }
<div class="intro" data-fade-toggle-config='{"selectors":{"trigger":".button","target":".heading"},"duration":3}'>
<h1 class="heading">Intro Heading</h1>
<p>This is the intro section</p>
<button class="button">Hide Heading</button>
</div>
<div class="main" data-fade-toggle-config='{"selectors":{"trigger":".button","target":".heading"}}'>
<h1 class="heading">Main Heading</h1>
<p>This is the main section</p>
<button class="button">Hide Heading</button>
</div>
... afternoon, improve the handling of state changes ...
There is still hard wired data, written directly into the code. In order to get rid of string-values that will be (re)rendered every time a toggle-change takes place one might give the data-based configuration-approach another chance.
This time each triggering element might feature a configuration that provides state depended values. Thus the initialization process needs to take care of retrieving this data and also of rendering it according to the initial state of a fade-toggle target.
This goal directly brings up the necessity of a render function for a trigger element because one needs to change a trigger's state not only initially but also with every fade-toggle.
And this again will change the handler function in a way that in addition it features bound state values too in order to delegate such data to the render process ...
class FadeToggle {
// a clean fade-toggle implementation.
constructor(elementNode, duration) {
duration = parseFloat(duration, 10);
duration = Number.isFinite(duration) ? duration : 1;
elementNode.style.opacity = 1;
elementNode.style.transition = `all ${ duration }s ease`;
this.element = elementNode;
}
isFadeoutActive() {
return this.element.classList.contains('fadeout-active');
}
toggleFade(duration) {
duration = parseFloat(duration, 10);
if (Number.isFinite(duration)) {
this.element.style.transitionDuration = `${ duration }s`;
}
if (this.isFadeoutActive()) {
this.element.style.opacity = 1;
this.element.classList.remove('fadeout-active');
} else {
this.element.style.opacity = 0;
this.element.classList.add('fadeout-active');
}
}
}
function renderTargetStateDependedTriggerText(target, trigger, fadeinText, fadeoutText) {
if ((fadeinText !== null) && (fadeoutText !== null)) {
if (target.isFadeoutActive()) {
trigger.textContent = fadeinText;
} else {
trigger.textContent = fadeoutText;
}
}
}
function handleFadeToggleWithBoundContext(/* evt */) {
// retrieve context data.
const { target, trigger, fadeinText, fadeoutText } = this;
target.toggleFade();
renderTargetStateDependedTriggerText(
target,
trigger,
fadeinText,
fadeoutText
);
}
function initializeFadeToggle(elmNode) {
// parse an element node's fade-toggle configuration.
let config = JSON.parse(elmNode.dataset.fadeToggleConfig || null);
const selectors = (config && config.selectors);
if (selectors) {
try {
// query both the triggering and the target element
const trigger = elmNode.querySelector(selectors.trigger || null);
let target = elmNode.querySelector(selectors.target || null);
if (trigger && target) {
// create a `FadeToggle` target type.
target = new FadeToggle(target, config.duration);
// parse a trigger node's fade-toggle configuration and state.
const triggerStates = ((
JSON.parse(trigger.dataset.fadeToggleTriggerConfig || null)
|| {}
).states || {});
// get a trigger node's state change values.
const fadeinStateValues = (triggerStates.fadein || {});
const fadeoutStateValues = (triggerStates.fadeout || {});
// get a trigger node's state change text contents.
const fadeinText = fadeinStateValues.textContent || null;
const fadeoutText = fadeoutStateValues.textContent || null;
// rerender trigger node's initial text value.
renderTargetStateDependedTriggerText(
target,
trigger,
fadeinText,
fadeoutText
);
// couple trigger and target by event listening/handling ...
trigger.addEventListener(
'click',
handleFadeToggleWithBoundContext.bind({
// ... and by binding both and some text values
// that are sensitive to state changes
// as context properties to the handler.
target,
trigger,
fadeinText,
fadeoutText
})
);
}
} catch (exception) {
console.warn(exception.message, exception);
}
}
}
function initializeEveryFadeToggle() {
// get list of all elements that contain a fade-toggle configuration
const configContainerList = document.querySelectorAll('[data-fade-toggle-config]');
// do initialization for each container separately.
configContainerList.forEach(initializeFadeToggle);
}
initializeEveryFadeToggle();
.as-console-wrapper { max-height: 100%!important; top: 0; }
<div class="intro" data-fade-toggle-config='{"selectors":{"trigger":".button","target":".heading"},"duration":3}'>
<h1 class="heading">Intro Heading</h1>
<p>This is the intro section</p>
<button class="button" data-fade-toggle-trigger-config='{"states":{"fadeout":{"textContent":"Hide Heading"},"fadein":{"textContent":"Show Heading"}}}'>Toggle Heading</button>
</div>
<div class="main" data-fade-toggle-config='{"selectors":{"trigger":".button","target":".heading"}}'>
<h1 class="heading">Main Heading</h1>
<p>This is the main section</p>
<button class="button">Toggle Heading</button>
</div>

This is happening because document.querySelector(".button") only returns the first element with class .button (reference).
You might want to try document.querySelectorAll(".button") (reference) to add your event listeners.
(Though this will only toggle your first heading - for the very same reason. ;))

Long magnetic scroll page in Ionic 2

Hey Guys i need your help please,
is started to working on an Ionic 2 App. My Navigation is not that complicated. I have one menu if i click one item another menu opens with a submenu and if i click on an item in the submenu a third page should render above it and this works really fine. Now the third activity should be a very long scrolling site with a lot of section (the sections are on top of each other). And every section should have a toolbar with one back button to go back to the submenu and two arrow keys for the previous or next section.
Here a small picture
now my problems:
how can i achieve the magnetic part? I think it like so: the Bar sits on the top of the page and above the content. When i scroll the content goes underneath and i can scroll to the end. When iam at the end everything should stop and when i pull further the next Section Bar jumps to the top of my site.
I hope you can help me thank you ;)

Plunker Demo
To make this work you need to:
Create a function that scrolls your scroll-content element to the top
Track the scroll position of scroll-content
Use *ngIf on your scroll to top button to conditionally show after scroll-content has reached a certain threshold.
Scroll to top function
I adapted this SO answer to apply to the scroll-content element
scrollToTop(scrollDuration) {
let scrollStep = -this.ionScroll.scrollTop / (scrollDuration / 15);
let scrollInterval = setInterval( () => {
if ( this.ionScroll.scrollTop != 0 ) {
this.ionScroll.scrollTop = this.ionScroll.scrollTop + scrollStep;
} else {
clearInterval(scrollInterval);
}
}, 15);
Track scroll-content position
This example uses the window height as the threshold for showing the scroll to top button like this:
this.ionScroll.addEventListener("scroll", () => {
if (this.ionScroll.scrollTop > window.innerHeight) {
this.showButton = true;
} else {
this.showButton = false;
}
});
Button Html
<button *ngIf="showButton" (click)="scrollToTop(1000)">Scroll Top</button>
Full component Typescript
import { NavController } from 'ionic-angular/index';
import { Component, OnInit, ElementRef } from "#angular/core";
#Component({
templateUrl:"home.html"
})
export class HomePage implements OnInit {
public ionScroll;
public showButton = false;
public contentData = [];
constructor(public myElement: ElementRef) {}
ngOnInit() {
// Ionic scroll element
this.ionScroll = this.myElement.nativeElement.children[1].firstChild;
// On scroll function
this.ionScroll.addEventListener("scroll", () => {
if (this.ionScroll.scrollTop > window.innerHeight) {
this.showButton = true;
} else {
this.showButton = false;
}
});
// Content data
for (let i = 0; i < 301; i++) {
this.contentData.push(i);
}
}
// Scroll to top function
// Adapted from https://stackoverflow.com/a/24559613/5357459
scrollToTop(scrollDuration) {
let scrollStep = -this.ionScroll.scrollTop / (scrollDuration / 15);
let scrollInterval = setInterval( () => {
if ( this.ionScroll.scrollTop != 0 ) {
this.ionScroll.scrollTop = this.ionScroll.scrollTop + scrollStep;
} else {
clearInterval(scrollInterval);
}
}, 15);
}
}
Full component Html
<ion-navbar primary *navbar>
<ion-title>
Ionic 2
</ion-title>
<button *ngIf="showButton" (click)="scrollToTop(1000)">Scroll Top</button>
</ion-navbar>
<ion-content class="has-header" #testElement>
<div padding style="text-align: center;">
<h1>Ionic 2 Test</h1>
<div *ngFor="let item of contentData">
test content-{{item}}
</div>
</div>
</ion-content>