Welcome to the reference guide for Lesson 3.4! Here you'll find key points and code snippets to help you recall and further understand the concepts we covered. Use this as a tool to review and reinforce your learning.

The Document Object Model (DOM) allows us to interact with and modify the structure, style, and content of websites using JavaScript. In this lesson, we learned about two properties: .innerHTML and .src.

• Definition: The .innerHTML property allows you to get or change the content of an HTML element.

• Usage:

  element.innerHTML = "New content here!";

• Example: If you have an HTML paragraph:

  <p id="demo">Hello, World!</p>

  Using JavaScript, you can change its content:

  document.getElementById("demo").innerHTML = "I'm different!";

• Definition: The .src property allows you to get or set the source URL of an <img> element.

• Usage:

  imageElement.src = "newImageURL.jpg";

• Example: Given an HTML image element:

  <img id="pic" src="oldImageURL.jpg">

  Using JavaScript, you can change its source URL:

  document.getElementById("pic").src = "newImageURL.jpg";

To make your changes more dynamic, you can attach events.

• Example:

  let button = document.querySelector("button");
  let header = document.querySelector("h1");
  
  button.addEventListener("click", function() {
      header.innerHTML = "This is important!";
  });

There are many types of events you can listen for, including:

• "click"
• "mouseover"
• "mouseout"
• "keydown"
• "keypress"

Usage:

element.addEventListener("eventtype", function() { 
  // actions to be executed 
});

Happy coding!