JavaScript: Set the background color of a paragraph

Last update on July 18 2025 12:59:19 (UTC/GMT +8 hours)

JavaScript DOM: Exercise-3 with Solution

Paragraph Background Color

Write a JavaScript program to set paragraph background color.

Sample Solution:

HTML Code:

<!-- Declaration of HTML document type -->
<!DOCTYPE html>
<!-- Start of HTML document -->
<html>
<!-- Start of head section -->
<head>
<!-- Declaring character encoding -->
<meta charset=utf-8 />
<!-- Setting title of the document -->
<title>Set the background color of a paragraph</title>
</head>
<!-- Start of body section -->
<body>
<!-- Button element triggering the set_background function on click -->
<input type="button" value="Click to set paragraph background color" onclick="set_background()">
<!-- First paragraph element -->
<p>w3resource JavaScript Exercises</p>
<!-- Second paragraph element -->
<p>w3resource PHP Exercises</p> 
<!-- End of body section -->
</body>
<!-- End of HTML document -->
</html>

JavaScript Code:

// Function declaration for set_background
function set_background() {
    // Getting reference to the body element
    docBody = document.getElementsByTagName("body")[0];
    // Get all the p elements that are descendants of the body
    myBodyElements = docBody.getElementsByTagName("p");
    // get the first p element
    myp1 = myBodyElements[0];
    // Setting background color for the first paragraph element
    myp1.style.background = "rgb(255,0,0)";
    // get the second p element
    myp2 = myBodyElements[1];
    // Setting background color for the second paragraph element
    myp2.style.background = "rgb(255,255,0)";
}

Output:

Flowchart:

Live Demo:

See the Pen javascript-dom-exercise-3 by w3resource (@w3resource) on CodePen.

For more Practice: Solve these Related Problems:

Write a JavaScript function that cycles through an array of background colors for the paragraph each time a button is clicked.
Write a JavaScript function that applies a random background color from a predefined palette to the paragraph on button click.
Write a JavaScript function that changes the paragraph’s background color based on the time of day (morning, afternoon, evening).
Write a JavaScript function that applies a CSS transition effect to smoothly change the paragraph's background color when the button is clicked.

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