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Highlighting every other row in a table can help make the data easier to read and interpret. When you have a large table with many rows, alternating the row colors allows the eye to more easily track across the rows and differentiate between them. This can be particularly helpful when reviewing data in a table for trends or patterns.
In this article, I’ll explain a few different methods for highlighting every other row in an HTML table, using just HTML and CSS. Whether you need this for a data-driven web page, an internal dashboard, or a simple way to showcase information, these techniques will help you implement row highlighting.
Using the :nth-child CSS Selector
One of the easiest ways to highlight every other row is by using the :nth-child CSS selector. This targets every element based on its numerical order and pattern.
To highlight every other row, you can target the odd or even rows like this:
“`css
tr:nth-child(even) {
background-color: #f2f2f2;
}
“`
Here’s an example HTML table with this CSS applied:
| Row 1 |
| Row 2 |
| Row 3 |
| Row 4 |
“`css
table {
border-collapse: collapse;
}
tr:nth-child(even) {
background-color: #f2f2f2;
}
“`
This highlights all the even rows with a light gray background color.
The `:nth-child()` selector is quite flexible too. You can use formulas like `2n` to target every 2nd element, or `2n+1` to target odd rows.
Adding CSS Classes to Rows
Another method is to add classes to the HTML rows and style those classes with CSS. For example:
“`html
…………“`
“`css
.odd {
background-color: #f2f2f2;
}
“`
While this requires a bit more markup, it keeps the styling code simple and maintainable. You don’t need to worry about complex CSS selectors.
You can toggle between two classes like “odd” and “even”:
“`html
………“`
Or use a single class and toggle it on and off:
“`html
………“`
This may be easier if styling an existing table where you don’t control the markup.
Using CSS Counters
For more programmatic control, you can use CSS counters to highlight rows based on a counter.
Here is an example:
“`css
tr {
counter-increment: rowNum;
}
tr:nth-child(odd) {
background-color: #f2f2f2;
}
tr:nth-child(even)::before {
content: counter(rowNum);
}
“`
This increments a “rowNum” counter on every row, highlights odd rows, and inserts the current counter value into even rows using a `::before` pseudo-element.
The counter lets you dynamically insert row numbers or apply other logic, while still alternating colors.
One catch is that CSS counters are not yet supported in some older browsers.
Using JavaScript
For the most flexibility, you can use JavaScript to programmatically highlight table rows. This allows highlighting rows based on any data or condition.
For example, you could highlight rows based on a threshold:
“`js
// Get all rows
const rows = document.querySelectorAll(‘tr’);
// Iterate through rows
rows.forEach(row => {
// Get data from this row
const value = parseInt(row.cells[0].textContent);
// Check if value exceeds threshold
if (value > 50) {
row.classList.add(‘highlight’);
} else {
row.classList.remove(‘highlight’);
}
});
“`
Or alternate coloring every other row:
“`js
// Get all rows
const rows = document.querySelectorAll(‘tr’);
// Iterate through rows
rows.forEach((row, i) => {
// Check if row index is even
if (i % 2 === 0) {
row.classList.add(‘highlight’);
} else {
row.classList.remove(‘highlight’);
}
});
“`
This gives you complete control to highlight any rows, based on any logic you want.
The downside is it requires adding JavaScript, rather than just HTML and CSS.
Summary
To recap, there are a few good options for highlighting every other row in an HTML table:
– Use the :nth-child() CSS selector to target odd or even rows
– Add CSS classes to alternate rows and style those classes
– Use CSS counters to programmatically number and target rows
– Write custom JavaScript to apply highlighting dynamically
The best method depends on your specific needs and table structure. The :nth-child selector works great for simple alternating row colors. For more complex logic, opt for CSS classes or JavaScript.
Hopefully this gives you some ideas to implement alternating row highlighting for your own data tables! Let me know if you have any other questions.
More Examples and Tips
Here are a few more examples and tips for highlighting rows:
**Combine :nth-child() with other selectors**
You can combine :nth-child() with element selectors to only highlight specific rows:
“`css
/* Highlight even TRs inside THEAD */
thead tr:nth-child(even) {
background: #ddd;
}
/* Highlight odd TRs inside TBODY */
tbody tr:nth-child(odd) {
background: #eee;
}
“`
**Highlight groups of rows**
Use nth-child formulas to highlight groups of rows:
“`css
/* Highlight in groups of 4 */
tr:nth-child(4n+1),
tr:nth-child(4n+2),
tr:nth-child(4n+3) {
background: #ddd;
}
“`
**Change border styles**
Along with background colors, you can modify borders to help rows stand out:
“`css
tr:nth-child(even) {
background: #eee;
border-top: 2px solid blue;
border-bottom: 2px solid blue;
}
“`
**Hover and focus styles**
Use the :hover and :focus pseudo-classes to create interactive row highlighting:
“`css
tr:hover {
background: yellow;
}
tr:focus {
outline: 1px solid red;
}
“`
This can create an accessible experience for keyboard and screen reader users.
**Zebra striping with CSS variables**
Here’s a clever way to “zebra stripe” rows using CSS custom properties:
“`css
:root {
–row-highlight: #ddd;
}
tr {
background: var(–row-highlight);
}
tr:nth-child(even) {
–row-highlight: initial;
}
“`
This makes it easy to change the highlight color in one spot.
I hope these examples give you more ideas for creatively highlighting rows! Let me know if you have any other questions.
Frequently Asked Questions
Here are some common questions about highlighting every other row in HTML tables:
How can I highlight rows on hover?
Use the :hover pseudo-class like this:
“`css
tr:hover {
background: #eee;
}
“`
How do I highlight rows based on data?
With JavaScript, you can add/remove classes based on data values. For example:
“`js
// Get all rows
const rows = document.querySelectorAll(‘tr’);
// Iterate through rows
rows.forEach(row => {
// Get data cell
const cell = row.querySelector(‘td.data’);
// Check value
if(cell.textContent > 50) {
row.classList.add(‘highlight’);
}
});
“`
Can this work with Angular, React, or Vue?
Yes, the same CSS and JavaScript techniques can be used. The framework components may generate slightly different markup, but the concepts are the same.
For example, in React you apply the CSS classnames to `
` components and write logic in component code.How do I number table rows?
Use the CSS counter technique. Increment a counter on each row, then use the `counter()` function to display it:
“`css
tr {
counter-increment: rowNum;
}
tr td:first-child::before {
content: counter(rowNum);
}
“`
This will insert the row number in the first cell.
Can I do this dynamically based on user interaction?
Yes, you can toggle the row highlighting dynamically by adding/removing classes in JavaScript. React to user events, filters, etc.
For example:
“`js
// Toggle on button click
button.addEventListener(‘click’, () => {
rows.forEach(t => t.classList.toggle(‘highlight’));
});
“`
Hope this helps cover some common use cases! Let me know if you have any other questions.
Conclusion
In summary, highlighting every other row in an HTML table can greatly improve the readability and scannability of tabular data. Whether you use basic CSS selectors, class names, counters, or custom JavaScript, there are many straightforward ways to implement alternating row colors or styling.
The best approach depends on the complexity of your data and the type of styling needed. For simple zebra striping, CSS nth-child selectors get the job done. For more advanced interactions, opt for JavaScript.
Hopefully this gives you some options to try for your own data tables. Proper row highlighting can make a table stand out while improving usability. Let me know if you have any other questions!
