> Also, DOM Strings are not UTF-16, they're UCS-16. Hm, according to the spec they should be interpreted as UTF-16 but this isn't enforced by the language so i

> Also, DOM Strings are not UTF-16, they're UCS-16. Hm, according to the spec they should be interpreted as UTF-16 but this isn't enforced by the language so it can contain unpaired surrogates: From https://heycam.github.io/webidl/#idl-DOMString https://heycam.github.io/webidl/#idl-DOMString > Such sequences are commonly interpreted as UTF-16 encoded strings [RFC2781] although this is not required... Nothing in this specification requires a DOMString value to be a valid UTF-16 string. From https://262.ecma-international.org/11.0/#sec-ecmascript-language-types-string-type https://262.ecma-international.org/11.0/#sec-ecmascript-lang... > The String type is the set of all ordered sequences of zero or more 16-bit unsigned integer values (“elements”) up to a maximum length of 253 - 1 elements. The String type is generally used to represent textual data in a running ECMAScript program, in which case each element in the String is treated as a UTF-16 code unit value... Operations that do interpret String values treat each element as a single UTF-16 code unit. However, ECMAScript does not restrict the value of or relationships between these code units, so operations that further interpret String contents as sequences of Unicode code points encoded in UTF-16 must account for ill-formed subsequences.