JavaScript Fundamentals · DOM · Lesson 24 of 48
Changing Content and Styles
Concept
Changing Content and Styles
Once selected, you can change an element's text with textContent and its appearance with the style property.
textContent is safer than innerHTML for plain text, since it never interprets the string as HTML — avoiding a common security pitfall when the text comes from user input.
By the end of this lesson
- Explain the core idea behind Changing Content and Styles.
- Predict output before running a change.
- Test one realistic and one unusual input.
- Use the result to make the next decision.
How to study this page
- 1. Read one concept.
- 2. Change the example.
- 3. Run, compare, and explain.
- 4. Complete the challenge below.
Syntax
element.textContent = "new text";
element.style.property = "value";
element.classList.add("className");ExampleRunnable
const box = document.querySelector(".box");
box.textContent = "Updated!";
box.style.color = "green";Toggling a CSS class instead
const box = document.querySelector(".box");
box.classList.toggle("active");Note: Toggling a class defined in your CSS is usually cleaner than setting inline styles one property at a time.
Self-check before continuing
Without looking at the example, describe what changes when you modify one input in Changing Content and Styles. Then reopen the editor and prove your explanation with a small test.
You are ready to continue when you can predict, test, and explain the result.
Your turn
Write code that changes a paragraph's text and makes it bold.
Loading editor…
Console