Overview
Introduction
Stripping a known prefix off the front of text, a protocol from a URL, a namespace from an identifier, is common enough to deserve a tool that only removes it when it's actually present.
It runs entirely client-side, so nothing you paste is ever uploaded to a server.
What Is Text Prefix Remover?
A prefix-removal tool that checks whether the input starts with your chosen prefix and, if so, strips exactly that many characters off the front.
It runs entirely client-side as part of this site's String Tools collection, so nothing you paste is ever uploaded to a server.
How Text Prefix Remover Works
The tool checks `input.startsWith(prefix)`; if true, it returns `input.slice(prefix.length)`, otherwise it returns the input unchanged.
The transformation happens synchronously in JavaScript the moment you type, with no network round trip involved.
When To Use Text Prefix Remover
Use it to strip a protocol like 'https://' from a URL, a namespace prefix from an identifier, or any other known leading string.
It's a fast way to get the answer without opening a code editor, a REPL, or writing a one-off script just to check.
Often used alongside String Prefix Adder, Line Prefix Adder and Whitespace Trimmer.
Features
Advantages
- Safe by design: it only removes the prefix when the text genuinely starts with it, so it never mangles unrelated input.
- Simple, predictable, single-pass behavior.
- Removes precisely the prefix's own length from the front, so it never cuts further into the text even when those characters recur later on.
Limitations
- Removes the prefix once from the whole input, not from every line.
- The match is case-sensitive and exact, so a differently-cased prefix won't be detected.
Examples
Best Practices & Notes
Best Practices
- Check the exact casing and characters of the prefix first, since the match is case-sensitive and won't remove a near-match.
- Include the trailing separator in the prefix, using 'https://' rather than 'https:', so no stray characters are left behind.
- Confirm the text actually changed, since a non-matching prefix returns the input untouched rather than reporting an error.
Developer Notes
The implementation guards with `prefix.length > 0 && input.startsWith(prefix)` before slicing, so an empty prefix or a non-matching input is returned unchanged rather than mutated.
Text Prefix Remover Use Cases
- Stripping 'https://' or 'http://' from a list of URLs
- Removing a namespace prefix from an identifier
- Cleaning a fixed label off values exported from another tool
Common Mistakes
- Expecting the prefix to be removed from every line of multi-line input, when it only checks the very start of the whole text.
- Specifying a prefix whose case differs from the text's, so the startsWith check fails and nothing at all is removed.
Tips
- Pair this with Add a Prefix to a String to round-trip a value: add a marker, transform it, then strip the marker back off.
- Because a non-match is a silent no-op, the tool is safe to run across a mixed list where only some values carry the prefix.