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How to call a function with arguments onclick of a button in a react component

Here is my function with arguments that i added in index.html in publics folder in a script tag
function displayContent(event, contentNameID) {
let content = document.getElementsByClassName("contentClass");
let totalCount = content.length;
for (let count = 0; count < totalCount; count++) {
content[count].style.display = "none";
}
let links = document.getElementsByClassName("linkClass");
totalLinks = links.length;
for (let count = 0; count < totalLinks; count++) {
links[count].classList.remove("active");
}
document.getElementById(contentNameID).style.display = "block";
event.currentTarget.classList.add("active");
}
Trying to call this function from click of buttons on my react component that looks like below
<button class="linkClass" onclick="displayContent(event, 'project2')">Meet at Campus
</button>
Please guide me with the syntax

Here's the correct syntax
<button className="linkClass" onClick={(event)=>displayContent(event,'project2')}>Meet at Campus</button>
Edit: please note that React components return JSX

It looks like you're trying to make some sort accordion but you shouldn't really be mixing vanilla JS with React as React needs control of the DOM.
So here's a brief example of how you might approach this using 1) state, and 2) a Panel component which comprises a button, and some content.
const { useState } = React;
function Example() {
// Initialise state with an array of false values
const [ state, setState ] = useState([
false, false, false
]);
// When a button in a panel is clicked get
// its id from the dataset, create a new array using `map`
// and then set the new state (at which point the component
// will render again
function handleClick(e) {
const { id } = e.target.dataset;
const updated = state.map((el, i) => {
if (i === id - 1) return true;
return false;
});
setState(updated);
}
// Pass in some props to each Panel component
return (
<div>
<Panel
name="Panel 1"
active={state[0]}
id="1"
handleClick={handleClick}
>
<span className="text1">Content 1</span>
</Panel>
<Panel
name="Panel 2"
active={state[1]}
id="2"
handleClick={handleClick}
>
<span className="text2">Content 2</span>
</Panel>
<Panel
name="Panel 3"
active={state[2]}
id="3"
handleClick={handleClick}
>
<span className="text3">Content 3</span>
</Panel>
</div>
);
}
function Panel(props) {
// Destructure those props
const {
name,
id,
active,
handleClick,
children
} = props;
// Return a div with a button, and
// content found in the children prop
// When the button is clicked the handler is
// called from the parent component, the state
// is updated, a new render is done. If the active prop
// is true show the content otherwise hide it
return (
<div className="panel">
<button data-id={id} onClick={handleClick}>
{name}
</button>
<div className={active && 'show'}>
{children}
</div>
</div>
);
}
ReactDOM.render(
<Example />,
document.getElementById('react')
);
.panel button:hover { cursor: pointer; }
.panel { margin: 1em 0; }
.panel div { display: none; }
.panel div.show { display: block; margin: 1em 0; }
.add { margin-top: 1em; background-color: #44aa77; }
.text1 { color: darkblue; font-weight: 600; }
.text2 { color: darkgreen; font-weight: 700; }
.text3 { color: darkred; font-weight: 300; }
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/17.0.2/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/17.0.2/umd/react-dom.production.min.js"></script>
<div id="react"></div>

Can't you use
document.getElementById("linkClass").onclick = () =>{
displayContent();
}
by giving the element an id with same of the class?

Hide/Show div and then hide all div

I am trying to make a "meet the staff" section that has hidden bios that display on click. Right now the div displays as it should, but only disappears when the original button is clicked again. I am needing some additional javascript to hide any opened divs when a different (or same) button is clicked. I don't know enough javascript to know what to try in order to make this happen. Thanks in advance!
HTML
<div id="lastname" class="toggle-div" style="display: none;">
<div><p>bio</p>
</div>
</div>
<button class="bio-button" onclick="myBiof()">Click for Bio</button>
Javascript
<script>
function myBiof() {
var y = document.getElementById("lastname");
if (y.style.display === "block") {
y.style.display = "none";
} else {
y.style.display = "block";
}
}
</script>

You will need to add some attributes to your HTML to keep track of which item is active, what item a button controls and which ones should be hidden from screen readers. aria-controls aria-expanded and aria-hidden do just that. Once a button is clicked... if it is currently open, just close it (remove active) and toggle the appropriate attributes. If it is not open, close all of them (remove active), open the one you clicked on (add active) and toggle the appropriate attributes. Here is a simple example:
const buttons = document.querySelectorAll("button");
const people = document.querySelectorAll(".person");
const handleClick = (event) => {
const clickedBtn = event.target;
if (clickedBtn.getAttribute("aria-expanded") === "true") {
let personId = clickedBtn.getAttribute("aria-controls");
let person = document.getElementById(personId);
person.classList.remove("active");
person.setAttribute("aria-hidden", "true");
clickedBtn.setAttribute("aria-expanded", "false");
} else if (clickedBtn.getAttribute("aria-expanded") === "false") {
people.forEach(person => {
person.classList.remove("active")
person.setAttribute("aria-hidden", "true");
});
buttons.forEach(button => button.setAttribute("aria-expanded", "false"));
let personId = clickedBtn.getAttribute("aria-controls");
let person = document.getElementById(personId);
person.classList.add("active");
person.setAttribute("aria-hidden", "false");
clickedBtn.setAttribute("aria-expanded", "true");
}
}
buttons.forEach(button => button.addEventListener("click", handleClick));
button {
display: block;
background: transparent;
border: none;
border-bottom: 1px solid #000;
width: 100%;
height: 2rem;
}
.person-container {
width: 400px;
margin: 0 auto;
}
.person {
display: none;
border-left: 1px solid #000;
border-right: 1px solid #000;
border-bottom: 1px solid #000;
padding: 1rem;
}
.person h2 {
margin-top: 0px;
}
.person p {
margin-bottom: 0px;
}
.active {
display: block;
}
<div class="person-container">
<button aria-controls="person-one" aria-expanded="false">Show Person One</button>
<div id="person-one" aria-hidden="true" class="person">
<h2>Name One</h2>
<p>Person One Bio</p>
</div>
<button aria-controls="person-two" aria-expanded="false">Show Person Two</button>
<div id="person-two" aria-hidden="true" class="person">
<h2>Name Two</h2>
<p>Person Two Bio</p>
</div>
<button aria-controls="person-three" aria-expanded="false">Show Person Three</button>
<div id="person-three" aria-hidden="true" class="person">
<h2>Name Three</h2>
<p>Person Three Bio</p>
</div>
</div>

/*
Function to add all the events to the buttons.
Checking if divs are hidden or not with [data-hidden] attribute.
This HMTML attributes can be named however you want but starting
with data-
Note that this code will only work if every button
is placed in the HTML after the bio div
*/
function addEventsAndListenToThem() {
const buttons = document.querySelectorAll('.bio-button')
buttons.forEach(btn => {
btn.onclick = (e) => {
const target = e.target.previousElementSibling
// If element is hided, show it changing
// attribute data-hidden value to false
target.getAttribute('data-hidden') === 'true' ?
target.setAttribute('data-hidden', 'false') :
target.setAttribute('data-hidden', 'true')
}
})
const hide_or_show_all = document.querySelector('.bio-button-all')
// Var to check wether .bio-button-all
// has been pressed or not
var showing = false
hide_or_show_all.onclick = () => {
// Get al divs with data-hidden property
const all_bios = document.querySelectorAll('div[data-hidden]')
showing === false ? (
() => {
// Show all divs
all_bios.forEach(bio => bio.setAttribute('data-hidden', 'false'))
showing = true
}
)() :
(
// Hide all divs
() => {
all_bios.forEach(bio => bio.setAttribute('data-hidden', 'true'))
showing = false
}
)()
}
}
addEventsAndListenToThem()
/*
Display none only to [data-hidden="true"] elements
*/
[data-hidden="true"] {
display: none;
}
.bio-button,
.bio-button-all {
display: block;
margin: 10px 0px;
}
<div id="lastname" class="toggle-div" data-hidden='true'>
<div>
<p>First bio</p>
</div>
</div>
<button class="bio-button">Click for first Bio</button>
<div id="lastname" class="toggle-div" data-hidden='true'>
<div>
<p>Second bio</p>
</div>
</div>
<button class="bio-button">Click for second Bio</button>
<div id="lastname" class="toggle-div" data-hidden='true'>
<div>
<p>Third bio</p>
</div>
</div>
<button class="bio-button">Click for third Bio</button>
<button class="bio-button-all">Show/Hide all</button>

VanillaJS - find middle element in the container

So I have a setup like this
<div class=“container”>
<div class=“segment segment1”></div>
<div class=“segment segment2”></div>
<div class=“segment segment3”></div>
.
.
.
<div class=“segmentN”></div>
</div>
Where N is an number defined by user so list is dynamical. For container I have applied styles to display it as grid, so EVERY time list has 3 items displayed, list is scrollable. My problem is, how can I via VanillaJS find element which is in the middle of container ? If there are 3 elements in the page, it should select 2nd one, when scrolling down it should select element which is in the middle of container every time to apply some styles to it in addition to grab it’s id. If there are 2 elements, it should select 2nd item as well. I was thinking about checking height of container, divide it by half and checking position of element if it’s in range. So far I was able to write this code in js
function findMiddleSegment() {
//selecting container
const segmentListContainer = document.querySelector(`.container`);
const rect = segmentListContainer.getBoundingClientRect();
//selecting all divs
const segments = document.querySelectorAll(`.segment`);
segments.forEach( (segment) => {
const location = segment.getBoundingClientRect();
if( (location.top >= rect.height / 2) ){
segment.classList.add(`midsegment`);
} else {
segment.classList.remove(`midsegment`);
}
});
}
But it doesn’t work. It finds element in the middle as should, but also applies style for every other element beneath middle segment. I’ve read some answers on stackoverflow, but couldn’t find any idea how to solve my problem.
EDIT
In addition to my problem I add additional function to show how I invoke it.
function handleDOMChange() {
findMiddleSegment(); //for "first run" when doc is loaded
const segmentListContainer = document.querySelector(`.container`);
segmentListContainer.addEventListener('scroll', findMiddleSegment);
}

A very easy way to do it is using the Intersection Observer:
const list = document.querySelector('ul'),
idDisplay = document.querySelector('p b');
const observer = new IntersectionObserver(
highlightMid,
{
root: list,
rootMargin: "-33.33% 0%",
threshold: .5
}
);
function makeList() {
list.innerHTML = '';
observer.disconnect();
const N = document.querySelector('input').value;
for (let i = 0; i < N;) {
const item = document.createElement('li');
item.id = `i_${++i}`;
item.textContent = `Item #${i}`;
list.append(item);
observer.observe(item);
}
};
function highlightMid(entries) {
entries.forEach(entry => {
entry.target.classList
.toggle('active', entry.isIntersecting);
})
const active = list.querySelector('.active');
if (active) idDisplay.textContent = '#' + active.id;
}
ul {
width: 50vw;
height: 50vh;
margin: auto;
padding: 0;
overflow-y: auto;
border: solid 1px;
}
li {
box-sizing: border-box;
height: 33.33%;
padding: .3em 1em;
list-style: none;
transition: .3s;
}
.active {
background: #6af;
}
<i>Make a list of:</i>
<input type="number" min="2" placeholder="number of items">
<button onclick="makeList()">make</button>
<p>Active id is <b>yet to set</b></p>
<ul></ul>

If container has only a list of segments inside, it's easer to count the element's children and find the mid element.
const segmentListContainer = document.querySelector(`.segmentListContainer`);
const midSegmentIndex = Math.floor(segmentListContainer.children.length / 2) - 1;
let midSegment = segmentListContaner.children[midSegmentIndex];
midSegment.classList.add('midsegment');
P.S.
The reason why your code adds 'mdsegment' to each element's class name after the real midsegment element is because of this conditional statement line you wrote.
if(location.top >= rect.height / 2){
segment.classList.add(`midsegment`);
}

Something like this. You can use Math.round, Math.ceil or Math.floor like I did. This works because querySelectorAll returns an array and you can use array.length to count the total number of items in the array then use a for loop to loop over all the segments and place the class based on the Math.(round, floor or ceil) based on your needs.
const container = document.querySelector(".container");
const segments = container.querySelectorAll(".segment");
const middleSegment = Math.floor(segments.length / 2);
for (let index = 0; index < segments.length; index++) {
segments[middleSegment].classList.add("middle-segment");
}
.middle-segment{
background-color: red;
}
<div class="container">
<div class="segment">segment</div>
<div class="segment">segment</div>
<div class="segment">segment</div>
<div class="segment">segment</div>
<div class="segment">segment</div>
<div class="segment">segment</div>
<div class="segment">segment</div>
</div>

You don't need javascript for this. CSS will do
.container {
width: 350px;
}
.container .segment {
width: 100px;
height: 100px;
float: left;
background-color: #EEE;
border: 1px dotted gray;
margin: 3px;
text-align: center;
color: silver;
}
.segment:nth-child(3n-1) {
background-color: aquamarine;
color: black;
}
<div class="container">
<div class="segment">segment</div>
<div class="segment">segment</div>
<div class="segment">segment</div>
<div class="segment">segment</div>
<div class="segment">segment</div>
<div class="segment">segment</div>
<div class="segment">segment</div>
<div class="segment">segment</div>
<div class="segment">segment</div>
<div class="segment">segment</div>
<div class="segment">segment</div>
<div class="segment">segment</div>
<div class="segment">segment</div>
<div class="segment">segment</div>
</div>

Focused elements display wrong style

I have element with width 400% and I want to move it to left by using translateX(-(index/4)*100%) when focused index changes.
Changing focused element translateX property with tab keyboard button displays it wrong on middle elements (1,2) even though using same hardcoded styling works as expected. What am I missing here?
const {useState} = React;
const App = () => {
const [curr, setCurr] = useState(0);
const carouselStyles = {
transform: `translateX(${-(curr / 4) * 100}%)`
// uncomment to see that styling works fine with hardcoded values 1,2..
// transform: `translateX(${-(1 / 4) * 100}%)`
};
const handleFocus = (num) => {
if (num !== curr) {
setCurr(num);
}
};
console.log(carouselStyles);
return (
<div>
<div className="carousel" style={carouselStyles}>
<div className="item">
11 very long text
<a href="/111" onFocus={() => handleFocus(0)}>
11111
</a>
</div>
<div className="item">
22 very long text
<a href="/222" onFocus={() => handleFocus(1)}>
22222
</a>
</div>
<div className="item">
33 very long text
<a href="/333" onFocus={() => handleFocus(2)}>
33333
</a>
</div>
<div className="item">
44 very long text
<a href="/444" onFocus={() => handleFocus(3)}>
44444
</a>
</div>
</div>
current: {curr}
</div>
);
}
// Render it
ReactDOM.render(
<App />,
document.getElementById("react")
);
.carousel {
display: flex;
align-items: center;
width: 400%;
}
.item {
flex: 0 1 100%;
text-align: center;
border: 1px solid black;
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.8.4/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.8.4/umd/react-dom.production.min.js"></script>
<div id="react"></div>

I needed to prevent the scrolling and in my provided example its enough to add this line into handleFocus function
window.scrollTo(0, 0);
But in my real scenario parent wrapper also had overflow: hidden; which prevented above code from working. So I've used refs
const handleFocus = (num) => {
if (num !== curr) {
setCurr(num);
carouselRef.current.scrollTo(0, 0);
}
};
return (
<div ref={carouselRef}>
<div className="carousel" style={carouselStyles}>
...
</div>
current: {curr}
</div>
);

How to find the index of an event target's parent node in JS?

When the page loads, an array is made that holds a group of divs and is used as a global variable catGroup. Each div has a button as a child, and when clicked, the target is saved as a global variable targ. What I'm trying to do is determine the index of the button's parent node every time it is clicked. I haven't been able to find a way to make this happen. Any help is appreciated.
i = catGroup.findIndex(node => node == targ.parentNode);

Wrap an element around all <div>s then register it to the click event:
document.querySelector('main').onclick = clickHandler;
Get the <div> of the button clicked by user:
const clicked = e.target;
const act = clicked.parentElement;
Collect all <div> that are direct descendants of <main>:
const divs = [...this.querySelectorAll('main > div')];
Remove '.active' from all <div> and then add .active to the parent <div> of clicked button:
divs.forEach(d => d.classList.remove('active'));
act.classList.add('active');
Filter the array of divs and return it's index:
idx = divs.flatMap((d, i) => d.className === 'active' ? i : []);
idx = divs.findIndex(d => d === act);
// As Peter Seliger suggested -- I brain farted
const main = document.querySelector('main');
main.onclick = getIndex;
function getIndex(e) {
let idx;
const clicked = e.target;
const divs = [...this.querySelectorAll('main > div')];
if (clicked.matches('[type="button"]') || clicked.matches('button')) {
const act = clicked.parentElement;
divs.forEach(d => d.classList.remove('active'));
act.classList.add('active');
idx = divs.findIndex(d => d === act);
}
document.querySelector('section').textContent = idx;
}
html {
font: 2ch/1 Consolas;
}
body {
position: relative;
height: 100vh
}
main {
padding: 5px 20px 10px;
}
section {
position: fixed;
top: 0;
left: 50%;
font-size: 5rem;
}
div {
width: 8.5ch;
text-align: center;
}
[type='button'], button {
display: block;
width: 10ch;
height: 3ch;
cursor: pointer;
}
<main>
<section></section>
<div><input type='button' value='0'></div>
<div><input type='button' value='1'></div>
<div><input type='button' value='2'></div>
<div><button>3</button></div>
<div><input type='button' value='4'></div>
<div><button>5</button></div>
<div><input type='button' value='6'></div>
<div><input type='button' value='7'></div>
<div><button>8</button></div>
<div><input type='button' value='9'></div>
</main>

This worked for me in a mouseover event. That's how I did it in my case:
onMouseOver={(e) => { const idx = Array.from(e.target.parentNode.children).indexOf(e.target); }}