How do I remove a trailing comma from the last line in a JSON array?

The TextKit Prefix/Suffix tool has a 'no trailing separator' toggle that handles this automatically. Manually: after the prefix/suffix pass, find/replace the final comma with nothing. The TextKit tool is faster — one toggle does it.

Can I prefix only some lines?

Not with a pure prefix/suffix tool. Use a regex find-and-replace on the line patterns you want to match. The Find & Replace tool with regex enabled handles selective prefixing.

What if my prefix or suffix contains special characters?

It just works — prefix/suffix tools treat the input as literal text, not patterns. Special regex characters, HTML entities, and quote marks all pass through as-is.

Why do I need a tool when I can just type the prefix in front of every line?

Speed. Twenty lines hand-edited takes a minute. Two thousand lines takes two minutes with a tool, two hours by hand. Past about ten lines, the tool wins on time.

Can I do this in VS Code without a separate tool?

Yes — multi-cursor mode (Cmd+D / Ctrl+D to add cursors at every line start) lets you type the prefix once and have it appear on every line. Works for up to a few hundred lines before performance degrades.

How to Add a Prefix or Suffix to Every Line

Wrap every line in a list with the same opening and closing text. Five common patterns: HTML lists, markdown bullets, JSON arrays, SQL IN clauses, CSV column. The browser shortcut for any of them is one paste.

The five patterns

Most prefix/suffix needs fall into one of five shapes:

Goal	Prefix	Suffix	Wrapper
HTML `<ul>`	`<li>`	`</li>`	`<ul>...</ul>`
Markdown bullet list	`-`	(none)	(none)
JSON string array	`"`	`",`	`[ ... ]`
SQL IN clause	`'`	`',`	`(...)`
CSV column with constant first column	`row,`	(none)	(none)

The Prefix & Suffix tool handles all five. Paste the lines, type the prefix and suffix, copy the result. Add the wrapper manually before pasting into the destination.

Worked example — building a SQL IN clause

Source list:

alice
bob
carol
dave

Want:

WHERE name IN ('alice', 'bob', 'carol', 'dave')

Steps:

Paste the list into the Prefix/Suffix tool.
Set prefix to ' (single quote).
Set suffix to ', (single quote, comma).
Toggle on "no trailing separator on last line."
Copy the output:
```
'alice',
'bob',
'carol',
'dave'
```
Paste between the parentheses of your IN ( ... ) clause.

Total time: ~5 seconds for any list size.

Worked example — building an HTML list

Source list of book titles. Want a clean <ul>.

Paste into the Prefix/Suffix tool.
Prefix: <li>
Suffix: </li>
Copy. Wrap manually with <ul>...</ul> at top and bottom.

For more complex HTML output (anchors, classes, data attributes), put the full HTML wrapper in the prefix:

Prefix: <li class="book"><a href="/books/
Suffix: ">view</a></li>

If your input is just slug-style identifiers, the output is a complete linked list ready to paste.

Worked example — JSON string array

Source list:

red
green
blue

Want:

["red", "green", "blue"]

Two ways:

Quick way (one-line array): use prefix ", suffix ",, "no trailing separator," then on output: replace newlines with spaces, wrap with [ and ].

Multi-line array (more readable): use prefix ", suffix ",, then add [ at the top and ] at the bottom in your text editor:

[
"red",
"green",
"blue"
]

For a real JSON parser, the trailing comma in the last line is invalid. The "no trailing separator" toggle handles this:

[
"red",
"green",
"blue"
]

The cleanup step everyone forgets

Three traps that bite if skipped:

Empty trailing line. If the input has a blank line at the end, the prefix/suffix gets applied to it, producing "", in the output. The tool's "skip empty lines" toggle prevents this.
Trailing comma on the last item. JSON parsers reject this. SQL parsers reject this. The "no trailing separator" toggle is the fix.
Quoting characters that need escaping. If your data contains the same character as your prefix/suffix (e.g., a single quote in the data when you're using single quotes as the prefix), you'll produce broken syntax. Pre-process to escape: replace ' with '' for SQL, or escape " with \" for JSON.

Wrap every line in seconds. The Prefix & Suffix tool handles HTML, markdown, JSON, SQL, and CSV patterns with toggles for empty-line skipping and trailing-separator handling.

Beyond the basic pattern

For more complex line wrapping (different prefix per line, conditional prefix, regex-based wrapping), drop to a programming editor with multi-cursor support (VS Code, Sublime, JetBrains IDEs) or a regex-aware find-and-replace tool. The Find & Replace tool with regex enabled can do conditional and pattern-based wrapping.

For the broader reference on list operations, see List Operations: The Complete Guide. For sorting before wrapping, see How to Sort Lines Alphabetically. For format conversion, see Format List for SQL/JSON/HTML.

Written by the TextKit team. We build the tools we write about — try the Prefix & Suffix tool used in this post.