DOM
Source: https://www.theodinproject.com/paths/foundations/courses/foundations/lessons/dom-manipulation-and-events
Create Element
const div = document.createElement('div');Append Element
append childNode as the last child of parentNode
parentNode.appendChild(childNode)
insert newNode into parentNode before referenceNode
parentNode.insertBefore(newNode, referenceNode)Remove Element
Remove child from parentNode on the DOM and return a reference to child
parentNode.removeChild(child) Inline Style
const div = document.createElement('div');
div.style.color = 'blue';
// adds the indicated style rule
div.style.cssText = 'color: blue; background: white';
// adds several style rules
div.setAttribute('style', 'color: blue; background: white');
// adds several style rules
div.style.background-color // doesn't work - attempts to subtract color from div.style.background
div.style.backgroundColor // accesses the div's background-color style
div.style['background-color'] // also works
div.style.cssText = "background-color: white" // ok in a stringEditing Attributes
div.setAttribute('id', 'theDiv');
// if id exists, update it to 'theDiv', else create an id
// with value "theDiv"
div.getAttribute('id');
// returns value of specified attribute, in this case
// "theDiv"
div.removeAttribute('id');
// removes specified attribute
// set property
div.style.setProperty('background-color','red');
// get property
console.log(div.style.getPropertyValue('background-color'));
Classes
div.classList.add('new');
// adds class "new" to your new div
div.classList.remove('new');
// removes "new" class from div
div.classList.toggle('active');
// if div doesn't have class "active" then add it, or if
// it does, then remove itText and HTML content
div.textContent = 'Hello World!'
// creates a text node containing "Hello World!" and
// inserts it in div
div.innerHTML = '<span>Hello World!</span>';
// renders the HTML inside divAttaching listeners to groups of nodes
<div id="container">
<button id="1">Click Me</button>
<button id="2">Click Me</button>
<button id="3">Click Me</button>
</div>
// buttons is a node list. It looks and acts much like an array.
const buttons = document.querySelectorAll('button');
// we use the .forEach method to iterate through each button
buttons.forEach((button) => {
// and for each one we add a 'click' listener
button.addEventListener('click', () => {
alert(button.id);
});
});
Source: https://www.theodinproject.com/paths/foundations/courses/foundations/lessons/dom-manipulation-and-events#eventsDom - Notes
Notes made from JavaScript DOM Crash Course - Traversy Media, source: https://youtu.be/0ik6X4DJKCc
Starter Template
<!doctype html>
<html lang="en">
<head>
<!-- Required meta tags -->
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<!-- Bootstrap CSS -->
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap@4.6.1/dist/css/bootstrap.min.css" integrity="sha384-zCbKRCUGaJDkqS1kPbPd7TveP5iyJE0EjAuZQTgFLD2ylzuqKfdKlfG/eSrtxUkn" crossorigin="anonymous">
<title>Item Lister</title>
</head>
<body>
<header id="main-header" class="bg-success text-white p-4 mb-3">
<div class="container">
<div class="row">
<div class="col-md-6">
<h1 id="header-title">Item Lister</h1>
</div>
<div class="col-md-6 align-self-center">
<input type="text" class="form-control" id="filter" placeholder="Search Items...">
</div>
</div>
</div>
</header>
<div class="container">
<div id="main" class="card card-body">
<h2 class="title">Add Items</h2>
<form id="addForm" class="form-inline mb-3">
<input type="text" class="form-control mr-2" id="item">
<input type="submit" class="btn btn-dark" value="Submit">
</form>
<h2 class="title">Items</h2>
<ul id="items" class="list-group">
<li class="list-group-item">Item 1 <button class="btn btn-danger btn-sm float-right delete">X</button></li>
<li class="list-group-item">Item 2 <button class="btn btn-danger btn-sm float-right delete">X</button></li>
<li class="list-group-item">Item 3 <button class="btn btn-danger btn-sm float-right delete">X</button></li>
<li class="list-group-item">Item 4 <button class="btn btn-danger btn-sm float-right delete">X</button></li>
</ul>
</div>
</div>
<!-- jQuery and Bootstrap Bundle (includes Popper) -->
<script src="https://cdn.jsdelivr.net/npm/jquery@3.5.1/dist/jquery.slim.min.js" integrity="sha384-DfXdz2htPH0lsSSs5nCTpuj/zy4C+OGpamoFVy38MVBnE+IbbVYUew+OrCXaRkfj" crossorigin="anonymous"></script>
<script src="https://cdn.jsdelivr.net/npm/bootstrap@4.6.1/dist/js/bootstrap.bundle.min.js" integrity="sha384-fQybjgWLrvvRgtW6bFlB7jaZrFsaBXjsOMm/tB9LTS58ONXgqbR9W8oWht/amnpF" crossorigin="anonymous"></script>
</body>
<script src="main.js"></script>
</html>Part 1
1. Examine the document object
// 1. EXAMINE THE DOCUMENT OBJECT
console.dir(document); print out all elements - #document
console.dir(document.domain); // 127.0.0.1
console.dir(document.URL); // http://127.0.0.1:5500/index.html?
console.dir(document.title); // Item Lister
document.doctype; //<!DOCTYPE html>
document.head; // <head>...</head>
document.body; // <body>...</body>
document.all; // HTMLCollection of all things in dom, e.g [html, head, meta, ..., body]
document.forms; // HTMLCollection of all forms
document.links; // HTMLCollection of all links
document.images; // HTMLCollection of all images
// Change element accessing document
document.title = 123 // 123
2. Get Element by ID
var headerTitle = document.getElementById('header-title'); // <h1 id="header-title">Item Lister</h1>
// Change element text
headerTitle.textContent = 'Hello'; // Change the element text, doesn't care about styling returns 'Hello'
headerTitle.innerText = 'Goodbye'; // Change the element text, take styling into consideration, returns 'Goodbye'
headerTitle.innerHTML = '<h3>Hello</h3>'; Put html element inside the selected element, <h1 id="header-title"><h3>Hello</h3></h1>
// Change element style
headerTitle.style.borderBottom = '1px solid blue'; // This allows you to choose any CSS property, but you need to use camel case, for example background-color is backgrounColor
3. Get Element by Class
var items = document.getElementsByClassName('list-group-item');
console.log(items); // Returns HTMLCollection, elements with indices, e.g. [li.list-group-item, li.list-group-item, ...]
items[1].textCOntent = 'Hello 2'; // access second item in HTMLCollection and change the text
items[1].style.fontWeight = 'bold'; // change style
items[1].style.backgroundColor = 'yellow'; // change style
// Change the style of all elements in the list
for (var i = 0; i < items.length; i++) {
items[i].style.backgroundColor = 'red';
}
4. Query Selector
var header = document.querySelector('#main-header'); // get the header with id main-header
header.style.borderBottom = '2px solid green';
// Get the input element
var input = document.querySelector('input');
input.value = 'Hello World'; // this will populate the value for selected input
// Get the input by it's type
var submit = document.querySelector('input[type="submit"]');
submit.value = "SEND"; // Change the button to SEND
// Get element using class (first li)
var item = document.querySelector('.list-group-item'); // this will get first element from ul list (first li)
item.style.color = 'red';
// Get last li element from the list
var lastItem = document.querySelector('.list-group-item:last-child');
// Get nth child li
var secondItem = document.querySelector('.list-group-item:nth-child(2)'); // Use css sudo selectors
5. Query Selector All
var titles = document.querySelectorAll('.title');
console.log(titles) // This will return: NodeList(2) [h2.title, h2.title] ; similar to HTMLCollection, but will allow to run array functions
titles[0].textContent = 'Hello'; // Access the first element from the node list and add text 'Hello'
// Use odd elements
var odd = document.querySelectorAll('li:nth-child(odd)');
var even = document.querySelectorAll('li:nth-child(even)');
// You can now edit all odd and even elements with for loop
for (car i = 0; i < odd.length; i++) {
odd[i].style.backgroundColor = '#f4f4f4';
even[i].style.backgroundColor = '#ccc';
}
Part 2
1. Traversing the DOM
var itemList = document.querySelector('#items'); // <ul id="items" class="list-group">…</ul>flex
// parentNode property
itemList.parentNode; // Returns parent element: <div id="main" class="card card-body">…<ul>..<ul></div>flex
itemList.parentNode.style.backgroundColor = '#f4f4f4'; // This will change the parent node
itemList.parentNode.parenNode; // This will give us the parent node of the parent node of the ul, we can move up in hierarchy like that
// parentElement property - can be used intechangeable with parentNode
itemList.parentElement; // Returns parent element: <div id="main" class="card card-body">…<ul>..<ul></div>flex
itemList.parentElement.style.backgroundColor = '#f4f4f4'; // This will change the parent node
itemList.parentElement.parentElement; // This will give us the parent element of the parent node of the ul, we can move up in hierarchy like that
// childNodes property - includes also text node (whitespace, line brakes etc.)
itemList.childNodes; // This will return NodeList(9) [text, li.list-group-item,...]
// children property - does not include white space text etc., only actual elements
itemList.children; returns HTMLCollection(4) [li.list-group-item, ...]
itemList.children[1]; // get second element from the collection
itemList.children[1].style.backgroundColor = 'yellow'; // change background-color property on the second element
// firstChild property
itemList.firstChild; // returns first item but it might be text (whitespace), like with childNodes property
// firstElementChild property
itemList.firstElementChild; // Returns first child: <li class="list-group-item">…</li>
// lastChild property
itemList.lastChild
// lastElementChild property
itemList.lastElementChild.textContent = 'Hello';
// nextSibling property
itemList.nextSibling;
// nextElementSibling property
itemList.nextElementSibling;
// previousSibling property
itemList.previousSibling;
// previousElementSibling property
itemList.previousElementSibling;
2. Create Element
// Create a div
var newDiv = document.createElement('div');
// Add class
newDiv.className = 'hello'; // <div class="hello"></div>
// Add ID
newDiv.id = 'hello1'; // <div class="hello" id="hello1"></div>
// Add attribute
newDiv.setAtrribute('title', 'Hello Div'); // <div class="hello" id="hello1" title="Hello Div"></div>
// Create text node
var newDivText = document.createTextNode('Hello World');
// Add text to div
newDiv.appendChild(newDivText); // <div class="hello" id="hello1" title="Hello Div">Hello World</div>
// Add created element to the DOM, get the hedaer container first
var container = document.querySelector('header .container');
var h1 = document.querySelector('header h1');
// Insert new element (newDiv) to container before h1
container.insertBefore(newDiv, h1); //
Part 3
Events
var button = document.getElementbyId('button');
button.addEventListener('click', function () {
// some function code
console.log('Test');
});
// Use named function
button.addEventListener('click', buttonClicked);
// named function
function buttonClicked () {
document.getElementById('header-title').textContent = 'Hello';
document.querySelector('#main').style.backgroundColor = '#f4f4f4';
};
// named function with Event passed as parameter
function buttonClicked(e) {
// Event objects
e.target; // Returns element that was clicked
e.target.id; // Returns id of the element
e.target.className;
e.target.classList; // Returns DomTokenList array, so list of all classes
var output = document.getElementById('output');
output.innerHTML = `<h3>${e.target.id}</h3>`;
e.type; // returns type of the event, e.g. click, input, submit etc.
e.clientX; // returns position of the mouse on the X axis from the browser window
e.clientY; // returns position of the mouse on the Y axis from the browser window
e.offsetX; // returns position of the mouse on the X axis from the actual element itself
e.offsetY; // returns position of the mouse on the Y axis from the actual element itself
e.altKey; // returns true (or false if not) if alt was pressed when event happened
e.ctrlKey; // true/false
e.shiftKey; // true/false
}
// Type of events
// Mouse Events
var button = document.getElementbyId('button');
button.addEventListener('dbclick', runEvent); // event fires on double click
button.addEventListener('mousedown', runEvent); // event if fired when mouse is clicked and hold
button.addEventListener('mouseup', runEvent); // event fires off when mouse is release
button.addEventListener('mouseenter', runEvent); // event fires off when you enter element
button.addEventListener('mouseleave', runEvent); // event fires off when you leave element
button.addEventListener('mouseover', runEvent); // event fires off when you enter child of the element
button.addEventListener('mouseout', runEvent); // event fires off when you leave child of the element
button.addEventListener('mousemove', runEvent); // grab the position of the mouse
// Keyboard Events
var itemInput = document.querySelector('input[type="text"]');
var form = document.querySelector('form');
form.addEventListener('keydown', runEvent);
form.addEventListener('keyup', runEvent);
form.addEventListener('keypress', runEvent);
// Text Events
itemInput.addEventListener('focus', runEvent); // when you select input field, it's active
itemInput.addEventListener('blur', runEvent); // when you leave field
itemInput.addEventListener('cut', runEvent); // fired when you cut the text
itemInput.addEventListener('paste', runEvent); // fired when you paste
itemInput.addEventListener('input', runEvent); // fired when you do anything with the input
var select = document.querySelector('select'); // We pretend that this element is dropdown list select
select.addEventListener('change', runEvent); // Event is fired on change, e.g. we select different value from select dropdown
form.addEventListener('submit', runEvent); // fired when you clicked submit for your form
function runEvent(e) {
e.preventDefault(); // prevent the default behaviour of the clicked element, e.g. form submission
e.type; // returns event type, e.g 'keydown'
output = `<h3>MouseX: ${e.offsetX}</h3><h3>MouseY: ${e.offsetY}</h3>`;
document.body.style.backgroundColor = `rgb(${e.offsetX},${e.offsetY},40)`; // this will change the background color based on the mouse move position
e.target.value; // if you use 'keydown' as event trigger on the form, you can captured what was typed in the input
}
Part 4
Real Example
var form = document.getElementById('addForm');
var itemList = document.getElementById('items');
var filter = document.getElementById('filter');
// Form submit event
form.addEventListener('submit', addItem);
// Delete event
itemList.addEventListener('click', removeItem);
// Filter event
filter.addEventListener('keyup', filterItems);
// Add item
function addItem(e) {
e.preventDefault();
// Get input value
var newItem = document.getElementById('item').value;
// Create new li element
var li = document.createElement('li');
// Add class name
li.className = 'list-group-item';
// Add text node with input value
li.appendChild(document.createTextNode(newItem));
// Create delete button element
var deleteBtn = document.createElement('button');
// Add classes to delete button
deleteBtn.className = 'btn btn-danger btn-sm float-right delete';
// Append text node
deleteBtn.appendChild(document.createTextNode('X'));
// Append button li
li.appendChild(deleteBtn);
// Append li to list
itemList.appendChild(li);
}
// Remove item
function removeItem(e) {
if (e.target.classList.contains('delete')) {
if (confirm('Are you sure?')) {
var li = e.target.parentElement;
itemList.removeChild(li);
}
}
}
// Filter items
function filterItems(e) {
// Convert text to lover case
var text = e.target.value.toLowerCase();
// Get all lis
var items = itemList.getElementsByTagName('li');
// Convert to an array
Array.from(items).forEach(function(item){
var itemName = item.firstChild.textContent;
if (itemName.toLowerCase().indexOf(text) != -1) {
item.style.display = 'block';
}
else {
item.style.display = 'none';
}
});
}Last updated
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