Strong random passwords from crypto.getRandomValues.
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Convert delimited text and JSON both ways.
Escape and unescape HTML and XML entities safely.
Convert 1-3999 both ways, see how each numeral adds up and catch non-standard forms like IIII.
Test any number for primality with Miller-Rabin, then get its prime factorisation and every divisor.
Mean, median, mode, quartiles, range and standard deviation for any list of numbers.
Add tax to a net amount or strip it back out of a gross amount, with common rates one click away.
