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JavaScript, the programming language that powers dynamic web content, becomes truly powerful when combined with the Document Object Model (DOM). The HTML DOM provides a structured representation of a document, allowing JavaScript to interact with and manipulate HTML elements. In this article, we’ll delve into essential JavaScript HTML DOM methods and explore their practical applications through examples.
- getElementById() Method:
ThegetElementById()method is a fundamental DOM method that allows you to access an HTML element by its unique identifier. Consider the following example:
<!DOCTYPE html>
<html>
<body>
<p id="demo">Hello, World!</p>
<script>
var element = document.getElementById("demo");
element.innerHTML = "Greetings, Earth!";
</script>
</body>
</html>Here, we retrieve the element with the ID “demo” and change its content using innerHTML.
- getElementsByClassName() Method:
This method returns a collection of elements with the specified class name. Let’s see it in action:
<!DOCTYPE html>
<html>
<body>
<p class="intro">This is an introduction.</p>
<p class="intro">Another introduction here.</p>
<script>
var elements = document.getElementsByClassName("intro");
for (var i = 0; i < elements.length; i++) {
elements[i].style.fontWeight = "bold";
}
</script>
</body>
</html>In this example, we select all elements with the class “intro” and change their font weight to bold.
- getElementsByTagName() Method:
This method retrieves a collection of elements with the specified tag name. Let’s demonstrate:
<!DOCTYPE html>
<html>
<body>
<ul>
<li>Item 1</li>
<li>Item 2</li>
<li>Item 3</li>
</ul>
<script>
var listItems = document.getElementsByTagName("li");
for (var i = 0; i < listItems.length; i++) {
listItems[i].style.color = "blue";
}
</script>
</body>
</html>Here, we select all list items (<li>) and change their text color to blue.
- createElement() and appendChild() Methods:
Creating new elements dynamically is a powerful feature. In this example, we create a new paragraph and append it to the document body:
<!DOCTYPE html>
<html>
<body>
<script>
var newParagraph = document.createElement("p");
var textNode = document.createTextNode("This is a dynamically created paragraph.");
newParagraph.appendChild(textNode);
document.body.appendChild(newParagraph);
</script>
</body>
</html>Here, createElement() creates a new <p> element, createTextNode() creates a text node, and appendChild() appends the text node to the paragraph, which is then appended to the body.
- addEventListener() Method:
This method is crucial for handling events. In this example, we add an event listener to a button:
<!DOCTYPE html>
<html>
<body>
<button id="myButton">Click me</button>
<script>
document.getElementById("myButton").addEventListener("click", function() {
alert("Button clicked!");
});
</script>
</body>
</html>When the button is clicked, an alert message will be displayed, showcasing the use of the addEventListener() method.
Conclusion:
Understanding and mastering JavaScript HTML DOM methods is essential for web developers. These methods provide the means to manipulate HTML elements dynamically, creating interactive and responsive web applications. By exploring and practicing these examples, developers can harness the full potential of JavaScript when working with the HTML DOM.
