Enhance your computer science education by delving into the exciting world of Javascript DOM Manipulation. This resource provides a comprehensive guide to understanding and applying these fundamental and advanced methods effectively. Starting with the basics for beginners, you'll explore the components, techniques, and practical applications of DOM Manipulation in JavaScript. Later sections shine a light on real-world examples, useful tools, tips for enhancing your skills and the importance of these methods for efficient programming. Ensuring your success, delve deeper into the subject, as you learn to illuminate your coding with JavaScript DOM Manipulation.
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Jetzt kostenlos anmeldenEnhance your computer science education by delving into the exciting world of Javascript DOM Manipulation. This resource provides a comprehensive guide to understanding and applying these fundamental and advanced methods effectively. Starting with the basics for beginners, you'll explore the components, techniques, and practical applications of DOM Manipulation in JavaScript. Later sections shine a light on real-world examples, useful tools, tips for enhancing your skills and the importance of these methods for efficient programming. Ensuring your success, delve deeper into the subject, as you learn to illuminate your coding with JavaScript DOM Manipulation.
The DOM (Document Object Model) is essentially a platform and language-neutral interface that allows scripts to dynamically access and update content, structure, and style of a document.
getElementById() | querySelector() |
createElement() | createTextNode() |
appendChild() | removeChild() |
replaceChild() | insertBefore() |
var element = document.createElement("h2"); var textNode = document.createTextNode("Hello World!"); element.appendChild(textNode); document.body.appendChild(element);
It's critical to note that modifying the DOM can become relatively expensive in terms of a page's performance. Therefore, it's a good idea to minimise direct manipulation of the DOM where possible. Virtual DOMs, such as those used by ReactJS, are a popular solution to this issue.
In the context of the Document Object Model, Nodes are any type of object within the DOM hierarchy, and Elements are a specific type of node that corresponds to the HTML tags in the markup language.
tag in your HTML:
var para = document.querySelector('p'); para.textContent = "New text!";
tag it finds in the Document and then changes its contents to "New text!".
Nodes and Elements: Almost everything in the HTML DOM is a node: the document itself is a document node, all HTML elements are element nodes, all HTML attributes are attribute nodes. Text inside HTML elements are text nodes. Comments are comment nodes.
querySelectorAll() | createTextNode() |
querySelector() | innerText |
getElementById() | innerHTML() |
var newEl = document.createElement('li'); var newText = document.createTextNode('Quinoa'); newEl.appendChild(newText); var position = document.getElementsByTagName('ul')[0]; position.appendChild(newEl);In this example, the code first creates a new list item and a new text node. It then appends the text node to the list item, and finally appends the list item to the unordered list in the HTML. Changing Attributes: Sometimes, the attribute of an element might need to be changed based on certain conditions or events. JavaScript allows you to do so using methods like getAttribute() and setAttribute().
var element = document.querySelector('img'); var sourceAttr = element.getAttribute('src'); element.setAttribute('src', 'newImage.png');Changing Styles: Another powerful aspect of DOM manipulation in JavaScript comes from its ability to alter the styles applied to an HTML element. This can be done using the style property.
var element = document.querySelector('p'); element.style.color = 'blue'; element.style.fontSize = '20px';In this example, we first select the paragraph element, then change its color to blue and font size to 20 pixels using the style property. Effectively manipulating the DOM is a key skill for any JavaScript developer. These techniques - adding and deleting nodes, changing attributes, and altering styles - are each vital tools you can utilise to build interactive and dynamic web pages. Practice using these methods and properties to become more comfortable with DOM manipulation and use JavaScript to its full potential!
var newElement = document.createElement("h2"); var newContent = document.createTextNode("This is the new H2 Heading"); newElement.appendChild(newContent); document.body.appendChild(newElement);In this code snippet, you first create a new `
var element = document.querySelector('p'); element.style.color = 'red'; element.style.fontSize = '18px';In this scenario, the first paragraph found will have its text colour change to red and its font size set to 18 pixels. DOM Manipulation Case 3: Removing an Element The following JavaScript code is a clear example of how you can remove an existing element from your HTML document using the `removeChild()` method.
var parentElement = document.querySelector('div'); var childElement = parentElement.querySelector('p'); parentElement.removeChild(childElement);This code selects the first `
` that is a child of the first `div` found and removes it from the HTML document. DOM Manipulation Case 4: Changing Attributes The following example shows how to change the value of an attribute using JavaScript. The `setAttribute()` function is used to change the existing attribute, or add a new attribute if it doesn't exist.
var element = document.querySelector('img'); element.setAttribute('src', 'newImage.png');The above code changes the `src` attribute of the first image found in the document to 'newImage.png'. DOM Manipulation case 5: Event Handling Event handling is an integral part of JavaScript DOM Manipulation. Events are actions that take place in the browser that can be detected by JavaScript, allowing dynamic interaction with web content. Here's a simple example of an event handler changing the content of a `
` tag when a button is clicked.
document.querySelector('button').addEventListener('click', function(e){ document.querySelector('p').textContent = 'The button was clicked!'; });In this case, an event listener is added to the button element that waits for a 'click'. When the button is clicked, the text content of the `
` tag is changed to 'The button was clicked!'. Each of these examples show you different dimensions of how you can use JavaScript to manipulate the DOM. Through them, you get hands-on practise of a variety of techniques that are regularly used in web development. Keep experimenting with these methods and you'll find yourself growing more confident and adept in your DOM manipulation skills.
$(document).ready(function() { $("p").click(function() { $(this).text("Paragraph clicked"); }); });This jQuery code sets the text of `
` elements to "Paragraph clicked" when clicked. D3.js: This is a powerful JavaScript library that lets you create interactive and visually appealing data visualisations using HTML, CSS, and SVG. It provides a variety of DOM manipulation methods specially tailored for data visualisation. Here's an example, where D3.js is used to create a bar chart:
var data = [4, 8, 15, 16, 23, 42]; var scale = d3.scaleLinear() .domain([0, d3.max(data)]) .range([0, 420]); d3.select(".chart") .selectAll("div") .data(data) .enter().append("div") .style("width", function(d) { return scale(d) + "px"; }) .text(function(d) { return d; });The code first scales the data, selects the chart class, and binds the data. The bar chart is then created using `.style()` and `.text()` methods. React.js: React is a JavaScript library developed by Facebook for building interactive user interfaces. It employs a virtual DOM which significantly improves the performance of complex or large web applications. Here's an example of a React component:
class Welcome extends React.Component { render() { returnThis code snippet defines a Welcome component, which renders a heading containing a greeting to the `name` provided via props. Each tool, whether jQuery, D3.js, or React.js, has its own strengths and characteristics, making it more suitable for different specific applications. Getting to know these tools and effectively using them in your work affords you greater command and control over DOM manipulation.Hello, {this.props.name}
; } }
document.getElementById('id') document.getElementsByClassName('className') document.getElementsByTagName('tagName') document.querySelector('cssSelector') document.querySelectorAll('cssSelector') element.innerHTML element.setAttribute(name, value) element.getAttribute(name) element.removeAttribute(name) element.style.propertyThese methods open up a myriad of opportunities for interacting with HTML documents and creating engaging, user-friendly web applications.
var element = document.getElementById('myElement'); element.style.color = 'blue'; element.style.backgroundColor = 'black';In the code snippet above, instead of querying the DOM twice for the same element, the element is stored in a variable and accessed from there. Avoid Inline Styles: It's always a better idea to manipulate classes instead of directly tweaking inline styles. Add, remove, or toggle classes on an element to get the changes you want. These tips can help ensure that your JavaScript program is efficient and responsive. Using the DOM manipulation methods in a consistent and optimised manner will result in a significant boon for your web development projects. As you foster these techniques, you will find yourself handling even the most complex JavaScript programs with ease and proficiency.
What is Javascript DOM Manipulation?
Javascript DOM Manipulation allows you to modify website content, alter its structure, and change styles directly with the use of JavaScript. This involves changing aspects like adding, modifying or deleting elements and attributes, changing the style or content of an element, and reacting to events like a mouse click.
What are common DOM manipulation methods in Javascript and how are they used?
Common DOM Manipulation methods in Javascript include: getElementById(), querySelector(), createElement(), createTextNode(), appendChild(), removeChild(), replaceChild() and insertBefore(). These methods help you locate and manipulate elements, specify where to include new elements or remove existing ones.
What are Nodes and Elements in the context of the Document Object Model (DOM)?
Nodes are any type of object within the DOM hierarchy, and Elements are a specific type of node that corresponds to the HTML tags in the markup language. A webpage is a large tree of these nodes, which can be Element nodes, Text nodes, or Comment nodes.
What are the core components of Advanced DOM Manipulation in JavaScript?
The core components of Advanced DOM Manipulation in JavaScript are Nodes and Elements, Events, and Methods and Properties. Each plays a vital role in the process of creating, editing, and interacting with web pages.
What are some techniques for implementing DOM manipulation in JavaScript?
Some techniques for implementing DOM manipulation in JavaScript include adding or deleting nodes, changing attributes, and altering styles. These methods allow you to programmatically change and interact with your web content.
How do you add a new node using JavaScript?
You can add a new node using methods like createElement() and appendChild(). First, create a new element and a new text node. Then, append the text node to the new element, and finally append the new element to the desired location in the HTML structure.
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