JavaScript: Highlight the bold words of a paragraph, on mouse over a certain link

Last update on July 18 2025 12:59:14 (UTC/GMT +8 hours)

JavaScript DOM: Exercise-12 with Solution

Highlight Bold on Hover

Write a JavaScript program to highlight the bold words of the following paragraph, on mouse over a certain link.

Sample link and text:

[On mouse over here bold words of the following paragraph will be highlighted]

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>Get And Style All Tags</title>
<!-- End of head section -->
</head>
<!-- Start of body section -->
<body> 
<!-- Paragraph containing a link -->
<p>[<a href="#" onMouseOver="highlight()" onMouseOut="return_normal()">On mouse over here bold words of the following paragraph will be highlighted</a>]</p> 
<!-- Paragraph with strong tags -->
<p><strong>We</strong> have just started <strong>this</strong> section for the users (<strong>beginner</strong> to intermediate) who <strong>want</strong> to work with <strong>various</strong> JavaScript <strong>problems</strong> and write scripts online to <strong>test</strong> their JavaScript <strong>skill</strong>.</p>
<!-- End of body section -->
</body>
<!-- End of HTML document -->
</html>

JavaScript Code:

// First create a list of all bold items 
var bold_Items;
// Execute getBold_items function when window is fully loaded
window.onload = getBold_items();
 
// Collect all <strong> tags
function getBold_items() 
{
    // Get all elements with tag name 'strong' and assign them to bold_Items variable
    bold_Items = document.getElementsByTagName('strong'); 
}

// Iterate all bold tags and change color  
function highlight() 
{
    // Loop through each element in bold_Items
    for (var i=0; i<bold_Items.length; i++)
    {                                                    
        // Change the color of the bold item to green
        bold_Items[i].style.color = "green";
    }
}

// On mouse out highlighted words become black
function return_normal()
{
    // Loop through each element in bold_Items
    for (var i=0; i<bold_Items.length; i++) 
    {
        // Change the color of the bold item back to black
        bold_Items[i].style.color = "black";
    }
}

Output:

Flowchart:

Live Demo:

See the Pen javascript-dom-exercise-12 by w3resource (@w3resource) on CodePen.

For more Practice: Solve these Related Problems:

Write a JavaScript function that highlights all bold (<strong> or <b>) elements in a paragraph when the user hovers over a specific link.
Write a JavaScript function that toggles a highlight class on bold words when the mouse enters and leaves a parent container.
Write a JavaScript function that changes the background color of bold text elements on hover.
Write a JavaScript function that uses event delegation to apply a CSS style to all bold text within a section when a hover event is triggered on a button.

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