Overview
Introduction
Applying the same small transformation, uppercasing, trimming, reversing, to every item in a list by hand is tedious and error-prone.
List Function Applier does exactly that in one pass: pick a function, and it's applied to every item while item order stays the same.
What Is List Function Applier?
A simple map operation for lists: choose one built-in function and it's applied to every item, producing a new list of the same length.
It supports the same configurable separator as the rest of the List category, so it works on newline-, comma-, or custom-delimited input.
How List Function Applier Works
The input is split into items on the resolved separator, then the chosen function (uppercase, lowercase, reverse, trim, or length) is applied to each item independently via Array.prototype.map.
The transformed items are rejoined using the same separator and delimiter as the input, so the list's overall shape is preserved even though each item's content changes.
When To Use List Function Applier
Use it to normalize case across a list of tags, usernames, or keys before comparing or deduplicating them.
It's also useful for quickly checking item lengths (with length-as-value) or cleaning up stray whitespace (with trim) across an entire pasted list.
Often used alongside List Inverter, List Reducer and List Item Indenter.
Features
Advantages
- Preserves item count and order exactly, only the content of each item changes.
- Covers the most common single-item transformations without needing five separate tools.
- Works with any separator, so it isn't limited to newline-delimited input.
Limitations
- Only one function per run; chain the output back in (or run twice) if you need to combine transformations.
- The "reverse" option reverses characters within each item, not the order of items, use List Reverser for that instead.
Examples
Best Practices & Notes
Best Practices
- Use lowercase before deduplicating a list of tags or usernames to catch case-only duplicates.
- Use trim first if your pasted list has inconsistent leading/trailing whitespace before applying another function.
Developer Notes
Character-level reversal uses [...item].reverse().join("") (spreading into an array of Unicode code points) rather than item.split(""), so most multi-byte characters survive the reversal intact.
List Function Applier Use Cases
- Normalizing the case of a list of environment variable names or feature flags
- Cleaning up whitespace across a pasted list before further processing
- Quickly eyeballing the length distribution of items in a list
Common Mistakes
- Expecting "reverse" to reverse the order of items rather than the characters inside each item.
- Running length-as-value and then trying to use the output as text again, it replaces content, it doesn't annotate it.
- Forgetting only one function applies per run when a combined transformation was actually needed.
Tips
- Chain this tool's output back into itself via "Send to tool" to apply a second function on top of the first.
- Use List Inverter instead if you specifically want character reversal as a dedicated, discoverable tool.