How can I add line numbers to an HTML textarea?

Adding Line Numbers to HTML Textarea: A Guide

When dealing with elements in HTML, displaying line numbers alongside the text can be a valuable feature for readability and editing accuracy. Let's explore a comprehensive solution to this task.

CodeMirror

The most recommended tool for adding line numbers to textareas is CodeMirror. It's a popular open-source JavaScript library that provides a wide range of features for text editing. To use CodeMirror, simply include the library and instantiate it with the appropriate options.

Live Demo

Here's a working demo illustrating the use of CodeMirror for line numbering:

var editor = CodeMirror.fromTextArea(document.getElementById('code'), {
    lineNumbers: true,
    mode: 'text/x-perl',
    theme: 'abbott',
});

<script src="https://cdnjs.cloudflare.com/ajax/libs/codemirror/6.65.7/codemirror.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/codemirror/6.65.7/mode/perl/perl.min.js"></script>
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/codemirror/6.65.7/codemirror.min.css">
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/codemirror/6.65.7/theme/abbott.min.css">

<textarea></textarea>

Additional Tips

If you're facing issues with line numbers not matching up with the actual lines, it's possible that your monitor's dots per inch (DPI) is set higher than 100%. CodeMirror takes this into account, but other solutions may not.

Conclusion

CodeMirror is a reliable and powerful solution for adding line numbers to textareas in HTML. It provides a range of customization options and integrates seamlessly with HTML elements.

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