Add Prefix/Suffix to Lines

This tool streamlines the process of batch-editing text by allowing you to prepend (add a prefix) or append (add a suffix) custom strings to each line of your input. It's a massive time-saver for developers, data analysts, content managers, and anyone who works with structured text. Instead of manually editing each line, which is tedious and prone to errors, you can apply a consistent format across thousands of lines in an instant.

The power of this utility lies in its simplicity and speed. All processing happens directly in your browser, ensuring that your data remains private and secure. There are no uploads and no waiting for a server to respond, making it an efficient part of any data cleaning or formatting workflow. Whether you're preparing a list for a web page, formatting log files for analysis, or just trying to make a list more readable, this tool handles the repetitive work for you.

How to Use:

• Input: Paste the text you want to modify into the input field. Each line break is treated as a new line to be processed.
• Prefix: Enter the text you want to add to the beginning of each line.
• Suffix: Enter the text you want to add to the end of each line.
• Click "Convert" and the tool will instantly generate the modified text in the output field. You can leave either the prefix or suffix field blank if you only need to add text to one end of the lines.

Example Use Cases:

• Web Development: Wrapping a plain text list of items with HTML list tags (<li> and </li>) to create a valid HTML list.
• Data Preparation: Adding quotation marks or other delimiters to every line to prepare data for import into a spreadsheet or database.
• Scripting: Prepending a specific command (like echo or git add) to a list of file paths for use in a shell script.
• Content Formatting: Adding a consistent marker, like a bullet point or number, to the beginning of each line in a document.

Technical Deep Dive

The core functionality of this tool is built upon fundamental JavaScript string and array manipulation methods, making it incredibly efficient and lightweight. When you click "Convert," the tool first takes the entire multi-line string from the input text area. It then uses the `split('\n')` method. This method breaks the string into an array of smaller strings, using the newline character (`\n`) as the delimiter. The result is an array where each element corresponds to a single line from your original text.

Next, the tool iterates over this new array using the `map()` method. The `map()` method is a powerful feature of modern JavaScript that creates a new array by applying a function to every element of an existing array. In this case, the function it applies is a simple string concatenation. For each line in the array, it constructs a new string like `(prefix) + (line) + (suffix)`. This uses template literals to efficiently combine the prefix you provided, the original line content, and the suffix.

After the `map()` operation completes, we have a new array where every line has been appropriately modified. The final step is to turn this array of strings back into a single, multi-line string that can be displayed in the output text area. This is achieved with the `join('\n')` method. It concatenates all the elements of the array into one string, inserting the newline character (`\n`) between each element.

The entire process is client-side, meaning it runs directly in your web browser. This has two significant advantages. First, it's incredibly fast because there's no network latency; you're not uploading your data to a server, waiting for it to be processed, and then downloading the result. The computation happens almost instantly on your own machine. Second, it's completely private. Because your data never leaves your computer, you can be confident that your information is secure and not being logged or stored elsewhere. This makes the tool safe to use even with sensitive or proprietary data. This client-side architecture is a core principle of our platform, providing a secure and responsive user experience. The simplicity of this implementation—relying on just `split`, `map`, and `join`—ensures maximum compatibility across all modern browsers and guarantees high performance even for very large inputs. It's a perfect example of leveraging core language features to build a fast, reliable, and secure web tool.