2.1.41 [ECMA-262/9:2018] Section 21.1.3.24 String.prototype.toLowerCase ( )

V0139: Results are derived according to the mappings in UnicodeData.txt, but not those in SpecialCasings.txt

The specification states:

 ... String.prototype.toLowerCase ( )
  
     This function interprets a String value as a sequence of UTF-16 encoded code points, 
     as described in 6.1.4. The following steps are taken:
         ...
  
     The result must be derived according to the locale-insensitive case mappings in the 
     Unicode Character Database (this explicitly includes not only the UnicodeData.txt 
     file, but also all locale-insensitive mappings in the SpecialCasings.txt file that 
     accompanies it).

EdgeHTML Mode

Results are derived according to the mappings in UnicodeData.txt, but not those in SpecialCasings.txt.

V0140: Only characters in the Basic Multilingual Plane are converted to lower case

The specification states:

 21.1.3.24 String.prototype.toLowerCase ( )
  
     This function interprets a String value as a sequence of UTF-16 encoded code points, 
     as described in 6.1.4. The following steps are taken:
  
         1. Let O be ? RequireObjectCoercible(this value).
         2. Let S be ? ToString(O).
         3. Let cpList be a List containing in order the code points as defined in 6.1.4 
            of S, starting at the first element of S.
         4. Let cuList be a List where the elements are the result of toLowercase(cplist), 
            according to the Unicode Default Case Conversion algorithm.
         5. Let L be the String value whose elements are the UTF16Encoding of the code 
            points of cuList.
         6. Return L.

EdgeHTML Mode

Only those characters in the Basic Multilingual Plane (values no greater than 0xFFFF) are converted to lower case. Others are left unchanged.