Overview
Introduction
Scanning a document for several different keywords at once, like a list of flagged terms or entities, is much slower to do by eye one term at a time.
It runs entirely client-side, so nothing you paste is ever uploaded to a server.
What Is Multi-Pattern Highlighter?
A multi-pattern highlighter that wraps every occurrence of any term from a comma-separated list with a marker string on both sides, matched case-insensitively.
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 Multi-Pattern Highlighter Works
The comma-separated terms are trimmed, escaped for safe regex use, sorted longest-first, and combined into a single alternation pattern so every occurrence of any term is wrapped with the marker in one pass.
The transformation happens synchronously in JavaScript the moment you type, with no network round trip involved.
When To Use Multi-Pattern Highlighter
Use it to spot several different keywords, entity names, or flagged terms across a document at once, without running a separate tool per term.
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 Letter Highlighter.
Features
Advantages
- Highlights an unlimited number of different terms in a single pass.
- Sorts terms longest-first internally to avoid a shorter term shadowing a longer one.
Limitations
- Matches terms as substrings, not whole words only, so a short term can match inside unrelated longer words.
Examples
Best Practices & Notes
Best Practices
- Use the Word Highlighter instead when you only need whole-word matching for a single term.
Developer Notes
Terms are escaped with `term.replace(/[.*+?^${}()|[\]\\]/g, "\\$&")`, sorted with `.sort((a, b) => b.length - a.length)`, and joined into `new RegExp(`(${escaped.join("|")})`, "gi")`, so the alternation tries longer terms before their shorter substrings.
Multi-Pattern Highlighter Use Cases
- Spotting several flagged keywords or entity names across a document
- Highlighting a set of related terms for a presentation or report
- Reviewing text for multiple search terms at once
Common Mistakes
- Expecting whole-word-only matching; short terms can match inside longer unrelated words.
- Forgetting the comma-separated format when entering multiple terms.
Tips
- List related terms together, like synonyms or variants of a keyword, to see their combined coverage in one highlighted pass.