How can JavaScript be used to create and manipulate HTML tags?
JavaScript dynamically creates, modifys, moves and deletes HTML elements through DOM operations. 1. Use document.createElement() to create a new element and add it to the page through appendChild() or insertBefore(); 2. Select existing elements through querySelector() or getElementById(), and modify them using textContent, innerHTML, setAttribute() and other methods; 3. When processing multiple elements through loops, you need to note that querySelectorAll() returns NodeList; 4. You can call appendChild() again when moving the element, and use .remove() when deleting it; 5. Dynamically set styles can be implemented through element.style or classList, and note that the style attribute name uses camelCase.
JavaScript is a powerful tool for creating and manipulating HTML elements dynamically. Whether you're building a single-page app or just adding interactivity to a static site, knowing how to work with the DOM using JavaScript is essential.
Creating Elements from Scratch
The most basic way to create an HTML element with JavaScript is by using document.createElement() . This method takes a string representing the tag name you want to create.
For example:
const newParagraph = document.createElement('p');
Once created, this element exists in memory but isn't yet part of the page. To make it visible, you need to append it to an existing element in the DOM. You can do that like this:
- Use
appendChild()to add it at the end of a parent node - Or use
insertBefore()to place it somewhere specific
Also, don't forget to set content inside your new element — usually done via textContent or innerHTML .
Modifying Existing Elements
To change something about an element that already exists on the page, you first need to select it using methods like querySelector() or getElementById() .
Once selected, you can:
- Change its text with
textContent - Update its HTML with
innerHTML - Modify attributes using
setAttribute() - Add or remove classes with
classList.add()/classList.remove()
Say you have a button and want to update its label dynamically based on some condition — this kind of manipulation makes that possible.
A common mistake here is forgetting that querySelectorAll() returns a NodeList, not a single element. So if you're trying to modify multiple items, be sure to loop through them.
Moving and Removing Elements
You're not limited to just adding or editing — JavaScript also lets you move or remove elements as needed.
If you want to move an element somewhere else on the page, just call appendChild() again, but this time with an element that's already in the DOM. The browser will automatically move it instead of duplicating it.
Removing is even simpler: call .remove() directly on the element you want to get rid of. Just make sure you're not removing something critical unless it's intentional.
One thing to watch out for: if you remove an element and then try to reuse it later, you'll need to re-append it. Once removed, it no longer exists in the DOM.
Setting Styles Dynamically
Sometimes you don't need to create or delete elements — you just want to tweak their appearance. JavaScript gives you two main options:
- Inline style via the
styleproperty - Adding/removing CSS classes with
classList
Using element.style.color = 'red' works for quick changes, but for more complex visual updates, toggling a class is usually cleaner and easier to maintain.
Keep in mind that when setting styles directly in JS, property names are written in camelCase rather than kebab-case. For example, background-color becomes backgroundColor .
Basically that's it.
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