Duplicate Word Highlighter
Finds case-insensitive word tokens that occur more than once anywhere in the input and marks every occurrence. It does not require adjacent duplicate words.
About this duplicate word highlighter
Finds case-insensitive word tokens that occur more than once anywhere in the input and marks every occurrence. It does not require adjacent duplicate words Applies Unicode-compliant text transformations and parsing directly in the browser tab without data leakage.
Text processing & transformation mechanics
Finds repeated case-insensitive Unicode letter/number/apostrophe/hyphen tokens anywhere in the input. Returns JSON with all duplicate keys and an HTML fragment whose original text is escaped while controlled <mark> tags wrap every matching occurrence.
Worked text manipulation example
Scenario: Show every repeated token, including tokens that are not adjacent.
Sample input:
Processing: Splits Unicode letter/number/apostrophe tokens, lowercases each token with locale rules, and marks every token whose key occurs more than once anywhere.
Illustrative output:
Character encoding & string length boundaries
This is exact-token repetition, not grammar or semantic analysis. The output is JSON text, not a rendered highlight. The highlighted field escapes original HTML-sensitive characters and inserts controlled <mark> tags; treat it as exported markup, not a sanitizer for later edits or unrelated HTML. Tokens made only of apostrophes or hyphens are not words.
Text formatting and transformations in Duplicate Word Highlighter preserve character integrity. Check edge cases such as multi-line inputs and special characters before downstream use.
In-memory text processing boundary
String operations and Unicode manipulations in Duplicate Word Highlighter execute entirely in local browser memory without transmitting input text.
Unicode Consortium & text formatting standards
Unicode Consortium standard annexes (UAX) and character encoding specifications:
- ECMAScript Unicode letter/number property matching and locale-aware lowercase comparison.
- CZOA-specific all-occurrence duplicate marking with HTML-escaped input and controlled <mark> tags; not Unicode word segmentation or an HTML sanitizer.
Duplicate Word Highlighter verification · Audit standards
How to use it
- Enter text in the input box, including any repeated words.
- Run locally to compare word-like tokens across the entire input without requiring adjacency.
- Read or copy the JSON duplicates list and the text containing literal <mark> tags in the output box.
Frequently asked questions
How does Duplicate Words Highlighter identify repeats?+
It splits the text into Unicode letter, number, apostrophe, and hyphen-like tokens, compares lowercase forms with `toLocaleLowerCase`, and marks every occurrence of a token that appears more than once anywhere in the text.
What local example can I run?+
Enter `One one TWO two!`. The result has `duplicates: ["one","two"]`, and every one of those four word occurrences is wrapped in `<mark>`; the exclamation mark remains unchanged.
Does it preserve the original token spelling?+
Yes for the rendered fragment: comparison ignores case, all duplicate occurrences retain their original spelling, and surrounding input is HTML-escaped (for example < becomes <). Only generated <mark> tags remain markup. The JSON output itself is shown as text.
Does it understand synonyms or language morphology?+
No. It compares normalized token strings only. Synonyms, stems, semantic repetition, and context are not detected.