Overview
Introduction
Finding every sentence in a long passage that mentions a specific keyword is slow to do by scanning manually, especially in a transcript or review document.
It runs entirely client-side, so nothing you paste is ever uploaded to a server.
What Is Sentence Highlighter?
A sentence highlighter that wraps every whole sentence containing a chosen keyword with a marker prefix and suffix, leaving sentences without the keyword completely untouched.
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 Sentence Highlighter Works
The input is split into sentences using a regex that captures runs of text up to and including their closing '.', '!', or '?' plus any trailing whitespace, then each sentence is checked case-insensitively for the keyword before wrapping its core text (excluding trailing whitespace) in the marker.
The transformation happens synchronously in JavaScript the moment you type, with no network round trip involved.
When To Use Sentence Highlighter
Use it to isolate relevant sentences in a long review, transcript, or article for a specific topic or keyword.
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 Word Highlighter and Multi-Pattern Highlighter.
Features
Advantages
- Operates at sentence granularity rather than word or letter level.
- Preserves the exact original spacing between sentences.
- Separates the trailing whitespace before wrapping, so the marker sits tight against the sentence rather than enclosing the gap that follows it.
Limitations
- Sentence splitting is a heuristic based on '.', '!', and '?'; it can misjudge abbreviations like 'Mr.' as sentence endings.
- Highlights the whole sentence rather than the keyword itself, so a long sentence is marked in full even when only one word matched.
Examples
Best Practices & Notes
Best Practices
- Use a specific, distinctive keyword to avoid matching more sentences than intended.
- Pick a marker that stands out clearly but does not occur naturally in the text, so the highlighted regions stay unambiguous.
- Run it before any reformatting, since sentence detection depends on the punctuation and spacing being exactly as written.
Developer Notes
Sentences are extracted via `input.match(/[^.!?]+[.!?]*(\s*|$)/g)`, and for each match, trailing whitespace is separated out with `sentence.match(/\s*$/)` so the marker wraps only the sentence's visible content, not the whitespace that follows it.
Sentence Highlighter Use Cases
- Isolating relevant sentences in a long review or transcript
- Highlighting topic-specific sentences in an article draft
- Preparing excerpts for a report by marking keyword sentences
Common Mistakes
- Expecting perfect sentence detection around abbreviations or decimal numbers, which can trigger false sentence breaks.
- Using a keyword that's too common, resulting in most sentences being highlighted.
Tips
- Pair with the Word Highlighter for a finer-grained view once you've isolated the sentences you care about.
- Counting the marker pairs tells you how many sentences matched, which is quicker than reading through a long highlighted passage.