In this code, I'm trying to assign DOM elements to variables, but variables get the value null. Why is it happening? Have I made some mistake?
<!DOCTYPE html>
<html>
<head>
<title>Tasks</title>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta name="description" content="A simple task list for your day-to-day.">
<meta name="author" content="Bruno M. B. Sdoukos">
<meta name="keywords" content="task list, checklist">
<script>
var taskCreator = document.querySelector('#taskcreator');
var list = document.querySelector('ul');
var taskInput = document.querySelector('#taskinput');
</script>
</head>
<body>
<ul></ul>
<input type="text" id="taskinput">
<button id="taskcreator">Create new item</button>
</body>
</html>
When browser executes your javascrit there is no input and button yet.
You can fix it with
<!DOCTYPE html>
<html>
<head>
<title>Tasks</title>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta name="description" content="A simple task list for your day-to-day.">
<meta name="author" content="Bruno M. B. Sdoukos">
<meta name="keywords" content="task list, checklist">
</head>
<body>
<ul></ul>
<input type="text" id="taskinput">
<button id="taskcreator">Create new item</button>
<script>
var taskCreator = document.querySelector('#taskcreator');
var list = document.querySelector('ul');
var taskInput = document.querySelector('#taskinput');
taskCreator.addEventListener('click', function createNewTask(event) {
list.innerHTML += '<li>' + taskInput.value + '</li>'
})
</script>
</body>
</html>
Or wait in the script until whole file will have been parsed.
<script>
document.addEventListener("DOMContentLoaded", function () {
var taskCreator = document.querySelector('#taskcreator');
var list = document.querySelector('ul');
var taskInput = document.querySelector('#taskinput');
taskCreator.addEventListener('click', function createNewTask(event) {
list.innerHTML += '<li>' + taskInput.value + '</li>'
})
});
</script>
https://developer.mozilla.org/ru/docs/Web/Events/DOMContentLoaded
Related
why doesn't it work? i just want to add a paragraph to a div. Guys, why doesn't it work? i just want to add a paragraph to a div.
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<script src="pobieranko.js"></script>
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<div class="klasa">lalal</div>
</body>
</html>
const divek = document.querySelector(".klasa")
const paragraf = document.createElement("p")
paragraf.textContent = "paragrafik"
divek.appendChild (paragraf);
It appears you did not add a script tag to the page as so:
<script>
const divek = document.querySelector(".klasa")
const paragraf = document.createElement("p")
paragraf.textContent = "paragrafik"
divek.appendChild (paragraf);
</script>
I'm working on an app that makes fetch calls to a dictionary API based on the user's input. The problem is, I can't seem to get the input value from the search bar. Currently, all that's being logged to the console is an empty string. I currently have my code inside of a DOMContentLoaded event listener. When I take my code out of the DOMContentLoaded function, I am getting a null value returned. This is incredibly straightforward but I can't seem to figure out what is getting muddled here. Here is the code;
window.addEventListener('DOMContentLoaded', () => {
const searchBar = document.getElementById('search-bar');
const userInput = searchBar.value;
const searchButton = document.getElementById('search-button');
const test = () => console.log(userInput);
searchButton.addEventListener('click', test);
});
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<script src="app.js"></script>
<title>Dictionary</title>
</head>
<body>
<h1>Dictionary</h1>
<input type="text" id="search-bar" placeholder="Find a definition"/>
<button id="search-button">Search</button>
<div id="results-area">
</div>
</body>
</html>
Thanks for the help.
The issue was you're getting always the first value of input which is empty, to get the new value call searchBar.value on the click of button.
window.addEventListener('DOMContentLoaded', () => {
const searchBar = document.getElementById('search-bar');
const searchButton = document.getElementById('search-button');
const getInputValue = () => {
let userInput = searchBar.value;
console.log(userInput);
}
searchButton.addEventListener('click', getInputValue);
});
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<script src="app.js"></script>
<title>Dictionary</title>
</head>
<body>
<h1>Dictionary</h1>
<input type="text" id="search-bar" placeholder="Find a definition" />
<button id="search-button">Search</button>
<div id="results-area">
</div>
</body>
</html>
hello my code isn't working idk why i tried to make textarea char counter that only shows the chachter not maxiumum
here is the java script
let text = document.querySelector('#text');
let number = text.value.length;
let count = document.querySelector('#count');
text.addEventListener("input", updateCount());
function updateCount(){
count.value + number
}
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Karakter sayısı</title>
<link rel="stylesheet" href="style.css">
</head>
<body>
<div class="ses">
<textarea id="text" placeholder="Yazıyı buraya Kopyala veya Yaz"></textarea>
</div>
<span id="filhu">Bu kadar yazdın:</span><span id="count">0</span>
<script src="main.js"></script>
</body>
</html>
In your text.addEventListener("input", updateCount()); assignment you did not assign the function updateCount to the input event of the selected element but instead you executed it once and assigned the non-existent return value of the function call to the event.
And in the function itself you will need to put (=assign) the calculated count somewhere too:
let text = document.querySelector('#text');
let count = document.querySelector('#count');
text.addEventListener("input", updateCount);
function updateCount(ev){
count.textContent=ev.target.value.length;
}
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Karakter sayısı</title>
<link rel="stylesheet" href="style.css">
</head>
<body>
<div class="ses">
<textarea id="text" placeholder="Yazıyı buraya Kopyala veya Yaz"></textarea>
</div>
<span id="filhu">Bu kadar yazdın:</span><span id="count">0</span>
<script src="main.js"></script>
</body>
</html>
ev.target.value.length gets the current length of the <textarea> element and count.textContent= assigns it to the target <span>.
A better way is by subscribing to the keyup event and getting the value from the scope using this keyword
function characterCount() {
document.getElementById('text').onkeyup = function () {
document.getElementById('count').innerHTML = this.value.length;
};
}
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Karakter sayısı</title>
</head>
<body>
<div class="ses">
<textarea id="text" placeholder="Yazıyı buraya Kopyala veya Yaz" onchange="characterCount()"></textarea>
</div>
<span id="filhu">Bu kadar yazdın:</span><span id="count">0</span>
</body>
</html>
I am trying to use HTML 'input' to change apiData.id value. I'm new to javascript and not sure if this is correct. Any suggestions would be greatly appreciated.
const apiData = {
url: 'https://pokeapi.co/api/v2/',
type: 'pokemon',
id: '76',
}
const input = document.getElementById('container');
const newId = apiData.id;
function eventController(event) {
newId = event.target.value;
}
input.addEventListener('change', eventController, false);
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Pokemon</title>
<link rel="stylesheet" href="style.css">
</head>
<body>
<div id="container">
<input id="input">
<input type="submit" value="Catch">
</div>
<div class="pokemon"></div>
<script src="main.js"></script>
</body>
</html>
newId is const, so you cannot assign it with a new value after it has been declared.
But even if you could (and you can, by making it a variable), that would not affect apiData.id, as newId is assigned with the value of apiData.id, but they are not bound together.
You should just assign apiData.id directly with a new value:
const apiData = {
url: 'https://pokeapi.co/api/v2/',
type: 'pokemon',
id: '76',
}
const input = document.getElementById('container');
// const newId = apiData.id;
function eventController(event) {
apiData.id = event.target.value;
}
input.addEventListener('change', eventController, false);
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Pokemon</title>
<link rel="stylesheet" href="style.css">
</head>
<body>
<div id="container">
<input id="input">
<input type="submit" value="Catch">
</div>
<div class="pokemon"></div>
<script src="main.js"></script>
</body>
</html>
How i'm supposed to select my element that have been created by function. First function is working well, but while i'm trying to select the element that been created in that function, it doesn't work
let d = document.querySelector(".lop");
let body = document.querySelector(".body");
d.addEventListener("click", function () {
let c = document.createElement("p");
c.appendChild(document.createTextNode("lopas"));
body.appendChild(c);
});
document.querySelector("p").addEventListener("click", function () {
console.log("Hi");
});
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta http-equiv="X-UA-Compatible" content="IE=edge" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>Document</title>
<link rel="stylesheet" href="style.css" />
</head>
<body>
<div class="lop">s</div>
<div class="body"></div>
<script src="script.js"></script>
</body>
</html>
That's because you are attempting to attach a click event to your paragraph tag before its ever been added to the DOM.
You will need to move this new event listener inside of your onclick and after you append it to your .body div.
Example:
let d = document.querySelector(".lop");
let body = document.querySelector(".body");
d.addEventListener("click", function () {
let c = document.createElement("p");
c.appendChild(document.createTextNode("lopas"));
body.appendChild(c);
document.querySelector("p").addEventListener("click", function () {
console.log("Hi");
});
});
As requested, here is how you could just split some of this out to be its own methods for clarity. Feel free to use your own style as its just an example:
const onClickLop = (e) => {
const el = document.createElement("p");
const bodyDiv = document.querySelector(".body");
el.appendChild(document.createTextNode("lopas"));
bodyDiv.appendChild(el);
el.addEventListener("click", onClickLopas);
};
const onClickLopas = (e) => {
console.log("Hi");
});
document.querySelector(".lop").addEventListener("click", onClickLop);
Problem:
You create the p element at the moment when you click on .lop
You try to add the event listener at the page load. At this point there is no p tag at all.
Solution:
Add the event listener after you created the p tag.
You could also use the reference c instead of querySelector.
let d = document.querySelector(".lop");
let body = document.querySelector(".body");
d.addEventListener("click", function() {
let c = document.createElement("p");
c.appendChild(document.createTextNode("lopas"));
body.appendChild(c);
c.addEventListener("click", function() {
console.log("Hi");
});
});
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta http-equiv="X-UA-Compatible" content="IE=edge" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>Document</title>
</head>
<body>
<div class="lop">s</div>
<div class="body"></div>
</body>
</html>
The code to add the event listener for the p element is executing before your code that creates it. Move the event handler into the first function so that it isn't triggered until the element is created and added to the document. However, that will mean that each time you click the first element, a new p will be created with its own handler (separate question/answer).
Also, by doing that you can consolidate some code.
let d = document.querySelector(".lop");
let body = document.querySelector(".body");
d.addEventListener("click", function () {
let c = document.createElement("p");
c.appendChild(document.createTextNode("lopas"));
c.addEventListener("click", function () {
console.log("Hi");
});
body.appendChild(c);
});
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta http-equiv="X-UA-Compatible" content="IE=edge" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>Document</title>
<link rel="stylesheet" href="style.css" />
</head>
<body>
<div class="lop">s</div>
<div class="body"></div>
<script src="script.js"></script>
</body>
</html>