What does the message "Range out of order in character class" mean in javascript?

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The message "Range out of order in character class" in JavaScript is an error that occurs when a range in a regular expression character class is specified in an incorrect order. The range in a character class is defined by two characters separated by a hyphen, and it should always have the smaller character first and the larger character last. When the order of the two characters is reversed or if there is a mistake in specifying the range, this error occurs.