ちゃんと読んだことなかったし, 電車移動中に暇だったのでとりあえず第 4 節まで読んだ (歴史とか用語定義とか).
おまけ
4.3.17 String value
primitive value that is a finite ordered sequence of zero or more 16-bit unsigned integer
NOTE A Sing value is a member of the String type. Each integer value in the sequence usually represents a single 16-bit unit of UTF-16 text. However, ECMAScript does not place any restrictions or requirements on the values except that they must be 16-bit unsigned integers.
(PDF 版より引用, 強調筆者)
急に歌うよ.