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Errors and edge cases

Return values

Section titled “Return values”
  • hamming() and normalizedHamming() return null when the strings have different lengths.
  • closest() returns null when no item matches the query, when the best match scores below minScore, or when the list is empty.
  • remove(index) on an index returns false for an index out of range (negative, or not less than size).
  • An index after destroy() does not throw. It behaves as an empty index and accepts new items.

What throws

Section titled “What throws”

Invalid arguments throw before any work is done. In Node.js most of them are an Error with the code InvalidArg. In the WebAssembly build they are an Error, a TypeError or a RangeError. Check for instanceof Error rather than a specific class.

  • maxResults, and the maxDistance threshold of levenshteinMany, damerauLevenshteinMany, indelMany, hammingMany and their *ManyU32 variants, must be a non-negative integer or Infinity (no limit). NaN, negative and fractional values throw.
  • A NaN minScore or minSimilarity throws. Any other number is accepted.
  • remove(index) throws a TypeError for an index that is not a number, and a RangeError for one that is not an integer (NaN, ±Infinity or a fraction).
  • *Batch functions throw when a pair is not exactly two strings.
  • In the WebAssembly build, a value that is not a string where a string is expected, an array that is not an array of strings, and a threshold that is not a number (such as '2' or true) throw a TypeError.
  • searchObjects() and FuzzyObjectIndex throw a TypeError when options.keys is missing or empty.
  • Object and keyed search throw when a weight is negative, NaN or infinite, or when the weights sum to 0 or overflow. The lower-level searchKeys() and KeyedFuzzyIndex also throw when the key text arrays have different lengths, or when the number of weights differs from the number of keys.
  • An unknown scoreMode or matchMode throws.
  • FuzzyIndex.deserialize(), KeyedFuzzyIndex.deserialize() and FuzzyObjectIndex.deserialize() throw on corrupt data and on data from another format version.
  • addMany() on KeyedFuzzyIndex and FuzzyObjectIndex is atomic: when one item is invalid, nothing is added, and the error names the item (item 3).