Calling a function from a JS file not working - javascript

I'm using React to view my pages.
I came across this problem if I try to call a function from a .js file nothing happens.
Basically, I have a small program that has two columns. Each column has a <p> tag that contains Column 1 and Column 2. There is a button below that once you click on it, both Columns should switch.
index.js
import "../style.css";
//import "./java.js";
class index extends React.Component {
render() {
return(
<div className="container">
<div className="columns" id="columnsToSwitch">
<div className="column1" id="column1_id">
<p>Column1</p>
</div>
<div className="column2" id="column2_id">
<p>Column 2</p>
</div>
</div>
<div className="switch" id="switch_id" onClick={this.switchColumns}>Switch</div>
</div>
);
}
}
export default index;
java.js
const switchCol = document.querySelectorAll("div.columns");
const el = document.getElementById("switch_id");
if(el) {
el.addEventListener("click", switchColumns, false);
}
switchCol.forEach(switches => switches.addEventListener('click', switchColumns));
function switchColumns(){
const makeSwitch1 = document.getElementById('column1_id');
document.getElementById('column2_id').appendChild(makeSwitch1);
const makeSwitch2 = document.getElementById('column2_id');
document.getElementById('column1_id').appendChild(makeSwitch2);
}
Method 1:
I tried to import the .js file that contains the function.
Nothing is happening after clicking "Switch".
Method 2:
Using onClick within a tag.
<div className="switch" id="switch_id" onClick={this.switchColumns}>Switch</div>
I get a couple of errors,
Uncaught TypeError: Cannot read properties of undefined (reading 'switchColumns')
The above error occurred in the <index> component:

On This line:
const switchCol = document.querySelectorAll(".switchCol");
There's no elements with the class of 'switchCol' so you're going to get an empty NodeList which causes the forEach loop to not execute so there are no click events on the columns themselves.
In the forEach block:
switchCol.forEach(switches => {
switches.addEventListener("column1", switchColumns);
switches.addEventListener("column2", switchColumns);
});
"column1" and "column2" are not valid event listeners, and there doesn't need to be two event listeners for one element. I think you mean to write the following:
switchCol.forEach(switch => switch.addEventListener('click', switchColumns))
Now onto your main switching column function:
function switchColumns(){
const makeSwitch1 = document.getElementById('column1');
document.getElementById('column2').appendChild(makeSwitch1);
const makeSwitch2 = document.getElementById('column2');
document.getElementById('column1').appendChild(makeSwitch2);
}
Variables makeSwitch1 and makeSwitch2 are going to be undefined as you do not have any elements with an id of column1 and column2 respectfully. Which is causing your issue with the second fix you tried.

Related

Can a javascript variable be made local to a specific html element?

As a novice Javascript programmer, I'd like to create an html document presenting a feature very similar to the "reveal spoiler" used extensively in the Stack Exchange sites.
My document therefore has a few <div> elements, each of which has an onClick event listner which, when clicked, should reveal a hiddent text.
I already know that this can be accomplished, e.g., by
<div onclick="this.innerHTML='Revealed text'"> Click to reveal </div>
However, I would like the text to be revealed to be initially stored in a variable, say txt, which will be used when the element is clicked, as in:
<div onclick="this.innerHTML=txt"> Click to reveal </div>
Since there will be many such <div> elements, I certainly cannot store the text to be revealed in a global variable. My question is then:
Can I declare a variable that is local to a specific html element?
Yes you can. HTML elements are essentially just Javascript Objects with properties/keys and values. So you could add a key and a value to an HTML element object.
But you have to add it to the dataset object that sits inside the element, like this:
element.dataset.txt = 'This is a value' // Just like a JS object
A working example of what you want could look like this:
function addVariable() {
const myElement = document.querySelector('div')
myElement.dataset.txt = 'This is the extended data'
}
function showExtendedText(event) {
const currentElement = event.currentTarget
currentElement.innerHTML += currentElement.dataset.txt
}
addVariable() // Calling this one immediately to add variables on initial load
<div onclick="showExtendedText(event)">Click to see more </div>
Or you could do it by adding the variable as a data-txt attribute right onto the element itself, in which case you don't even need the addVariable() function:
function showExtendedText(event) {
const currentElement = event.currentTarget
currentElement.innerHTML += currentElement.dataset.txt
}
<div onclick="showExtendedText(event)" data-txt="This is the extended data">Click to see more </div>
To access the data/variable for the specific element that you clicked on, you have to pass the event object as a function paramater. This event object is given to you automatically by the click event (or any other event).
Elements have attributes, so you can put the information into an attribute. Custom attributes should usually be data attributes. On click, check if a parent element has one of the attributes you're interested in, and if so, toggle that parent.
document.addEventListener('click', (e) => {
const parent = e.target.closest('[data-spoiler]');
if (!parent) return;
const currentMarkup = parent.innerHTML;
parent.innerHTML = parent.dataset.spoiler;
parent.dataset.spoiler = currentMarkup;
});
<div data-spoiler="foo">text 1</div>
<div data-spoiler="bar">text 2</div>
That's the closest you'll get to "a variable that is local to a specific html element". To define the text completely in the JavaScript instead, one option is to use an array, then look up the clicked index of the spoiler element in the array.
const spoilerTexts = ['foo', 'bar'];
const spoilerTags = [...document.querySelectorAll('.spoiler')];
document.addEventListener('click', (e) => {
const parent = e.target.closest('.spoiler');
if (!parent) return;
const currentMarkup = parent.innerHTML;
const index = spoilerTags.indexOf(parent);
parent.innerHTML = spoilerTexts[index];
spoilerTexts[index] = currentMarkup;
});
<div class="spoiler">text 1</div>
<div class="spoiler">text 2</div>
There are also libraries that allow for that sort of thing, by associating each element with a component (a JavaScript function/object used by the library) and somehow sending a variable to that component.
// for example, with React
const SpoilerElement = ({ originalText, spoilerText }) => {
const [spoilerShown, setSpoilerShown] = React.useState(false);
return (
<div onClick={() => setSpoilerShown(!spoilerShown)}>
{ spoilerShown ? spoilerText : originalText }
</div>
);
};
const App = () => (
<div>
<SpoilerElement originalText="text 1" spoilerText="foo" />
<SpoilerElement originalText="text 2" spoilerText="bar" />
</div>
)
ReactDOM.createRoot(document.querySelector('.react')).render(<App />);
<script crossorigin src="https://unpkg.com/react#18/umd/react.development.js"></script>
<script crossorigin src="https://unpkg.com/react-dom#18/umd/react-dom.development.js"></script>
<div class='react'></div>
Thanks everybody for your answers, which helped immensely! However, as a minimalist, I took all that I learned from you and came up with what I believe is the simplest possible code achieving my goal:
<div spoiler = "foo" onclick="this.innerHTML=this.getAttribute('spoiler')">
Click for spoiler
</div>
<div spoiler = "bar" onclick="this.innerHTML=this.getAttribute('spoiler')">
Click for spoiler
</div>

How can I save buttons in variable, created by Element.insertAdjacentHTML() method?

as I said in title I have problem with HTML elements created with Element.insertAdjacentHTML() method, I'm trying about an hour to solve this but can't. I have button that create new HTML elements, couple of that elements is new buttons with same class or id, it's no matter, that I need to catch in some variable and than again use for event listener, for some reason the class or id for these new created button doesn't exist, is there any way to catch it and use it later, I need Vanila Javascript?
There is over 500 lines of code, this is only for mentioned method
btnClaim.addEventListener("click", () => {
rewardCurrent.style.display = "none";
claimedRewards.push(currentReward);
rewardsList.innerHTML = ``;
claimedRewards.forEach(function (rew, i) {
const html = `
<div class="reward" id="${i}">
<div class="img-text-cont">
<img src="${rew.imgUrl}" alt="">
<div class="text-cont">
<p class="claimed-reward-title">${rew.title}</p>
<p class="claimed-reward-price">$${rew.price}</p>
</div>
</div>
<div class="claimed-rewards-action">
<button id="btn-sell2">Sell</button>
<button id="btn-ship">Ship</button>
</div>
</div>
`;
rewardsList.insertAdjacentHTML("afterbegin", html);
I need that btn-sell2 and btn-ship buttons in variables.
your element is going to be created and doesn't exist at the time page loads, so js addeventlistener will throw an error. to solve you have 2 ways.
1- use parent node that element will be created inside.
addevenlistener to parent and use
parent.addeventlistener( event, function (event){
if(event.target.classList.contains("childClass") {}
}
2- give addeventlistener when creating the element :
function createElement () {
const elem = -craete elemnt-
elem.addeventlistener(event, function);
}

Add onclick or eventListener in insertAdjacentHTML in react-js

I am building a simple react app for learning purpose, I just started learning react-js, I was trying to add paragraph dynamically on user action and it worked perfectly But I want to add an onClick event in insertAdjacentHTML (basically innerHTML).
But onclick event is not working in innerHTML
app.js
const addParagraph = () => {
var paragraphSpace = document.getElementById('container')
paragraphSpace.insertAdjacentHTML('beforeend', `<p>I am dynamically created paragraph for showing purpose<p> <span id="delete-para" onClick={deleteParagraph(this)}>Delete</span>`
}
const deleteParagraph = (e) => {
document.querySelector(e).parent('div').remove();
}
class App extends React.Component {
render() {
return (
<div>
<div onClick={addParagraph}>
Click here to Add Paragraph
</div>
<div id="container"></div>
</div>
)
}
}
What I am trying to do ?
User will be able to add multiple paragraphs and I am trying to add a delete button on every paragraph so user can delete particular paragraph
I have also tried with eventListener like :-
const deleteParagraph = () => {
document.querySelector('#delete').addEventListener("click", "#delete",
function(e) {
e.preventDefault();
document.querySelector(this).parent('div').remove();
})
}
But It said
deleteParagraph is not defined
I also tried to wrap deleteParagraph in componentDidMount() But it removes everything from the window.
Any help would be much Appreciated. Thank You.
Do not manipulate the DOM directly, let React handle DOM changes instead. Here's one way to implement it properly.
class App extends React.Component {
state = { paragraphs: [] };
addParagraph = () => {
// do not mutate the state directly, make a clone
const newParagraphs = this.state.paragraphs.slice(0);
// and mutate the clone, add a new paragraph
newParagraphs.push('I am dynamically created paragraph for showing purpose');
// then update the paragraphs in the state
this.setState({ paragraphs: newParagraphs });
};
deleteParagraph = (index) => () => {
// do not mutate the state directly, make a clone
const newParagraphs = this.state.paragraphs.slice(0);
// and mutate the clone, delete the current paragraph
newParagraphs.splice(index, 1);
// then update the paragraphs in the state
this.setState({ paragraphs: newParagraphs });
};
render() {
return (
<div>
<div onClick={this.addParagraph}>Click here to Add Paragraph</div>
<div id="container">
{this.state.paragraphs.map((paragraph, index) => (
<>
<p>{paragraph}</p>
<span onClick={this.deleteParagraph(index)}>Delete</span>
</>
))}
</div>
</div>
);
}
}
insertAdjecentHTML should not be used in javascripts frameworks because they work on entirely different paradigm. React components are rerendered every time you change a component state.
So you want to manipulate look of your component by changing its state
Solution:
In constructor initialize your component's state which you will change later on button click. Initial state is array of empty paragraphs.
constructor() {
super()
this.state = {
paragraphs:[]
}
}
And alter that state on button click - like this:
<div onClick={addParagraph}>
Add Paragraph function
const addParagraph = () =>{
this.state = this.state.push('New paragraph')
}
Rendering paragraphs
<div id="container">
this.state.paragraphs.map(paragraph =>{
<p>{paragraph}</p>
})
</div>
Additional tip for ReactJS in 2022 - use Functional components instead of Class components

Is there any way to bind a div which is created after DOM loaded and add event on it on vanila JS?

currently I am making my own project and I got stuck in :/
I wanted to add an event and give some function on div which is made with a button("create"). However, the console returned "Uncaught TypeError: Cannot read property 'addEventListener' of null" this. I think it is because DIV(.c) is made after JS run.
But I need to add an eventlistener and function on DIV(.c) to accomplish what I want.
So, is there any way to bind a div which is created later and add an
const createButton = document.querySelector(".create");
const paperBook = document.querySelector(".b");
createButton.addEventListener("click", createWriting);
function createWriting(e) {
e.preventDefault();
const writing = document.createElement("div");
writing.classList.add("c");
writing.innerHTML = `All work No rest make jack a dull boy`;
paperBook.appendChild(writing);
}
const myProblem = document.querySelector(".c");
myProblem.addEventListener("click", randomFunction);
function randomFunction(e) {
e.preventDefault();
console.log(e)
}
<div class="a">
<button class="create">create</button>
<div class="b"></div>
</div>
event on it?
Below is my code. But I summarized it to simplify for you if you need a whole code just ask me, please :)
thx!
I think the problem is that this part of code
const myProblem = document.querySelector(".c");
It is executed before you create your .c element, so the new elements would not be included on it. Try to add the event everytime a new element is created in the createWriting function
const createButton = document.querySelector(".create");
const paperBook = document.querySelector(".b");
createButton.addEventListener("click", createWriting);
function createWriting(e) {
e.preventDefault();
const writing = document.createElement("div");
writing.classList.add("c");
writing.innerHTML = `All work No rest make jack a dull boy`;
paperBook.appendChild(writing);
writing.addEventListener("click", randomFunction);
}
function randomFunction(e) {
e.preventDefault();
console.log(e)
}
<div class="a">
<button class="create">create</button>
<div class="b"></div>
</div>

React Hooks: useState with onClick only updating the SECOND time button is clicked?

Edit: forgot an important part - this is noticeable if you click the button next to Jeff A. Menges and check the console log.
The important part of the code is the "setFullResults(cardResults.data.concat(cardResultsPageTwo.data))" line in the onClick of the button code. I think it SHOULD set fullResults to whatever I tell it to... except it doesn't work the first time you click it. Every time after, it works, but not the first time. That's going to be trouble for the next set, because I can't map over an undefined array, and I don't want to tell users to just click on the button twice for the actual search results to come up.
I'm guessing useEffect would work, but I don't know how to write it or where to put it. It's clearly not working at the top of the App functional component, but anywhere else I try to put it gives me an error.
I've tried "this.forceUpdate()" which a lot of places recommend as a quick fix (but recommend against using - but I've been trying to figure this out for hours), but "this.forceUpdate()" isn't a function no matter where I put it.
Please help me get this button working the first time it's clicked on.
import React, { useState, useEffect } from "react";
const App = () => {
let artistData = require("./mass-artists.json");
const [showTheCards, setShowTheCards] = useState();
const [fullResults, setFullResults] = useState([]);
useEffect(() => {
setFullResults();
}, []);
let artistDataMap = artistData.map(artistName => {
//console.log(artistName);
return (
<aside className="artist-section">
<span>{artistName}</span>
<button
className="astbutton"
onClick={ function GetCardList() {
fetch(
`https://api.scryfall.com/cards/search?unique=prints&q=a:"${artistName}"`
)
.then(response => {
return response.json();
})
.then((cardResults) => {
console.log(cardResults.has_more)
if (cardResults.has_more === true) {
fetch (`https://api.scryfall.com/cards/search?unique=prints&q=a:"${artistName}"&page=2`)
.then((responsepagetwo) => {
return responsepagetwo.json();
})
.then(cardResultsPageTwo => {
console.log(`First Results Page: ${cardResults}`)
console.log(`Second Results Page: ${cardResultsPageTwo}`)
setFullResults(cardResults.data.concat(cardResultsPageTwo.data))
console.log(`Full Results: ${fullResults}`)
})
}
setShowTheCards(
cardResults.data
.filter(({ digital }) => digital === false)
.map(cardData => {
if (cardData.layout === "transform") {
return (
//TODO : Transform card code
<span>Transform Card (Needs special return)</span>
)
}
else if (cardData.layout === "double_faced_token") {
return (
//TODO: Double Faced Token card code
<span>Double Faced Token (Needs special return)</span>
)
}
else {
return (
<div className="card-object">
<span className="card-object-name">
{cardData.name}
</span>
<span className="card-object-set">
{cardData.set_name}
</span>
<img
className="card-object-img-sm"
alt={cardData.name}
src={cardData.image_uris.small}
/>
</div>
)
}
})
)
});
}}
>
Show Cards
</button>
</aside>
);
});
return (
<aside>
<aside className="artist-group">
{artistDataMap}
</aside>
<aside className="card-wrapper">
{showTheCards}
</aside>
</aside>
);
};
export default App;
CodesAndBox: https://codesandbox.io/embed/compassionate-satoshi-iq3nc?fontsize=14
You can try refactoring the code like for onClick handler have a synthetic event. Add this event Listener as part of a class. Use arrow function so that you need not bind this function handler inside the constructor. After fetching the data try to set the state to the result and use the state to render the HTML mark up inside render method. And when I run this code, I have also seen one error in console that child elements require key attribute. I have seen you are using Array.prototype.map inside render method, but when you return the span element inside that try to add a key attribute so that when React diffing algorithm encounters a new element it reduces the time complexity to check certain nodes with this key attribute.
useEffect(() => {
// call the functions which depend on fullResults here
setFullResults();
}, [fullResults])
// now it will check whether fullResults changed, if changed than call functions inside useEffect which are depending on fullResults

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