JS1023: Expected hexadecimal digit

Code includes an incorrect Unicode escape sequence, or a non-hexadecimal character is the first character in a hexadecimal literal.

Unicode escape sequences begin with /u, followed by exactly four hexadecimal digits. Hexadecimal literals begin with 0x, followed by any number of hexadecimal digits. Hexadecimal digits can contain only the numbers 0-9, the uppercase letters A-F, and the lowercase letters a-f. The following example demonstrates a correctly formed Unicode escape sequence.

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z = "/u1A5F";

The following example demonstrates a correctly formed hexadecimal literal.

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k = 0x3E8;

To correct this error

1. Be sure that hexadecimal numbers contain only the numbers 0-9, the uppercase letters A-F, and the lowercase letters a-f.

2. Be sure that the Unicode escape sequence contains four digits.

   Note:
   If you want to use the literal text /u in a string, then use two backslashes - (//u) — one to escape the first backslash.