Decodes String objects encoded with the escape function.
The required charString argument is a String object or literal to be decoded.
The unescape function returns a string value that contains the contents of charstring. All characters encoded with the %xx hexadecimal form are replaced by their ASCII character set equivalents.
Characters encoded in %uxxxx format (Unicode characters) are replaced with the Unicode character with hexadecimal encoding xxxx.
The unescape function should not be used to decode Uniform Resource Identifiers (URI). Use decodeURI and decodeURIComponent functions instead.