Censoring

censor returns the text with every match masked. Everything else, including spacing, punctuation and emoji, is left as it was.

censor('you muji');             // 'you ****'
censor('F.U.C.K this Sh1t!');   // '******* this ****!'
censor('मुजीको क्लास');          // '*** क्लास'
censor('Great teacher!');       // 'Great teacher!'

Check and censor in one pass

To find out whether text has profanity and get a censored copy, use check. It scans the text once and returns a result you can read and then censor, so you don't pay for a second scan:

final result = check('you muji, F.U.C.K');

result.hasProfanity;   // true
result.words;          // ['muji', 'fuck']
result.censor();       // 'you ****, *******'

Because censor() is a method on the result, you can chain it:

check('you muji').censor();              // 'you ****'
check('you muji').censor(mask: '#');     // 'you ####'

A common pattern is to save the censored text and flag the original for a moderator:

final result = check(commentText);

await comments.add({
  'body': result.censor(),
  'flagged': result.hasProfanity,
  'flaggedWords': result.words,
});

Calling containsProfanity(text) and then censor(text) gives the same result, but scans the text twice.

Change the mask

mask sets the string used in place of each character of a match. The default is *.

censor('you muji', mask: '#');   // 'you ####'
censor('you muji', mask: '•');   // 'you ••••'

Custom replacements

replace receives each match and returns the text to put in its place. It takes precedence over mask.

// A fixed label
censor('you muji', replace: (m) => '[censored]');
// 'you [censored]'

// Keep the first letter
censor('you muji', replace: (m) => m.text[0] + '*' * (m.text.length - 1));
// 'you m***'

// Grawlix
censor('you muji', replace: (m) => ('@#\$%&!' * m.text.length).substring(0, m.text.length));
// 'you @#$%'

// Wrap it for your UI instead of hiding it
censor('you muji', replace: (m) => '<mark>${m.text}</mark>');
// 'you <mark>muji</mark>'

The match is the same as the ones returned by findProfanityMatches:

Field	Example	Meaning
text	'F.U.C.K'	Exactly what the user typed.
normalized	'fuck'	The normalized form that matched.
start	0	Start index in the input.
end	7	End index in the input, exclusive.

In Flutter, to style matches rather than replace them, build a TextSpan from the positions instead; see Highlight matches.

With filter options

censor and check accept the same languages and strictness options as every other function:

censor('fuck muji', languages: [Language.romanized]);            // 'fuck ****'
censor('you idiot', strictness: Strictness.lenient);             // 'you idiot'
check('you idiot', strictness: Strictness.lenient).censor();     // 'you idiot'

A ProfanityFilter has check and censor too:

final filter = ProfanityFilter(languages: [Language.romanized, Language.devanagari]);

filter.censor('fuck muji');         // 'fuck ****'
filter.check('मुजी').censor();       // '**'

What gets masked

• Exactly the characters the user typed. Positions are traced back through normalization, so leetspeak (Sh1t), ! for i (sh!!t), full-width letters (ＦＵＣＫ) and zero-width characters are masked in full.
• Spelled-out words, dots included. F.U.C.K becomes *******.
• One mask character per visible character. Devanagari is counted by what you see, not by code unit, so मुजी becomes **, not ****.
• Whitespace inside a phrase is kept. sasto manche becomes ***** ******.
• Overlapping matches are merged. chaak ko pwal is a phrase that contains the word chaak, and it's masked once, as ***** ** ****.
• Postpositions are masked with the word. mujiko becomes ******, because the filter reads it as one word.