What is DOM (Document Object Model)? How to manipulate DOM elements using JavaScript?

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⭐ What is DOM?

DOM, the Document Object Model, is a programming interface used to access and manipulate the structure of HTML and XML documents. It represents the entire document as a tree structure, with each node representing an element, attribute, or text in the document. DOM provides a way to connect web content and scripting languages ​​(such as JavaScript), allowing developers to use scripting languages ​​to dynamically access and modify document content, structure, and style.

⭐ How to manipulate DOM elements using JavaScript?

Manipulating DOM elements with JavaScript is a common task in front-end development, allowing you to modify web pages in a way that responds to user interaction or dynamically updates page content.

Here are some common ways to manipulate DOM elements:

1. Get DOM elements

To manipulate DOM elements, you first need to get references to them. You can use one of the following methods:

• Get an element by ID: Use document.getElementById()the method to get a reference to an element by its ID.

  const myElement = document.getElementById('my-element');
  

• Get elements through selectors: Use document.querySelector()the method to get the first matching element through a CSS selector.

  const element = document.querySelector('.my-class');
  

• Get elements by tag name: Use document.getElementsByTagName()the method to get a set of elements by tag name.

  const paragraphs = document.getElementsByTagName('p');
  

• Get elements by class name: Use document.getElementsByClassName()the method to get a set of elements by class name.

  const elements = document.getElementsByClassName('my-class');
  

2. Modify element content

Once you have references to DOM elements, you can modify their content, such as text or HTML.

• Modify the text content of the element: Use the textContentor innerTextattribute to set the text content of the element.

  myElement.textContent = '新的文本内容';
  

• Modify the HTML content of an element: Use innerHTMLthe attribute to set the HTML content of an element.

  myElement.innerHTML = '<strong>加粗文本</strong>';
  

3. Modify element attributes

You can use JavaScript to modify an element's properties.

• Modify element properties: Use dot notation or setAttribute()the method to modify the properties of an element.

  myElement.setAttribute('src', 'new-image.jpg');
  

4. Adding and removing elements

You can add new elements to the DOM or remove existing elements via JavaScript.

• Create a new element: Use document.createElement()the method to create a new element and then add it to the DOM.

  const newElement = document.createElement('div');
  document.body.appendChild(newElement);
  

• Deleting an element: Use remove()the method or call removeChild()the method on the parent element to delete the element.

  myElement.remove();
  

5. Add and remove event listeners

JavaScript allows you to add event listeners to DOM elements in response to user interaction.

• Add an event listener: Use addEventListener()the method to add an event listener to an element.

  myElement.addEventListener('click', myFunction);
  

• Remove an event listener: Use removeEventListener()the method to remove an event listener from an element.

  myElement.removeEventListener('click', myFunction);
  

These are some basic DOM manipulation methods that allow you to modify the content and behavior of web pages in a dynamic and interactive way. By using JavaScript, you can interact with DOM elements and create interactive web applications.

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