dataURI-text-charset.txt

data:text/plain;charset=sjis,%82%a0
data:text/plain;charset=euc-jp,%a4%a2

data:text/plain;charset=utf8,%E3%81%82
data:text/plain;charset=utf8,%EF%BB%BF%E3%81%82

// URLは勝手にUTF8にエンコードされる <- ブラウザによる模様
// "\u{0030}\u{0042}" === "0B"
data:text/plain;charset=UTF-16,%ff%fe%42%30
data:text/plain;charset=UTF-16,%ff%feB0
data:text/plain;charset=UTF-16,%42%30
data:text/plain;charset=UTF-16,B0

data:text/plain;charset=UTF-16BE,%fe%ff%30%42
data:text/plain;charset=UTF-16BE,%fe%ff0B
data:text/plain;charset=UTF-16BE,%30%42
data:text/plain;charset=UTF-16BE,0B

data:text/plain;charset=utf-16be;base64,MEI=

data:text/plain;charset=utf-8;base64,44GC

// Pythonから取ると楽  'あ'.encode()
btoa("\xE3\x81\x82")
btoa("\u00E3\u0081\u0082")
btoa("あ")


- 大文字小文字は関係ない
- 複数の表記が可能なものが一部にある
- エラーはブラウザーコンソールに表示される
- 優先順位は BOM > charset

UTF8
UTF-8

sjis
Shift_JIS
shift-jis

string-char-code.js

// あ
// E38182 UTF-8
// 3042   UTF-16 hex
// 12354  UTF-16 decimal (0x3042)

// older
"あ".charCodeAt(0);         // 12354
String.fromCharCode(12354); // "あ"
// newer
"あ".codePointAt(0)         // 12354
String.fromCodePoint(12354) // "あ"
encodeURI("あ");            // "%E3%81%82"
"\u3042" === "あ";
"\u{3042}" === "あ";

[0xE3, 0x81, 0x82];                           // [227, 129, 130]
["e3", "81" ,"82"].map(e=> parseInt(e, 16));  // [227, 129, 130]
[227, 129 ,130].map(e=> e.toString(16));      // ["e3", "81", "82"]

0x3042;              // 12354
parseInt(3042, 16);  // 12354
12354..toString(16); // "3042"

new TextEncoder().encode("あ");              // [227, 129, 130] (Uint8Array)

var buffer = new ArrayBuffer(3);
var view   = new Uint8Array(buffer);
[0xE3, 0x81, 0x82].forEach((e, i)=> {
  view[i] = e
});

new TextDecoder().decode(view); // "あ"

toFile.js

// data:text/plain;charset=sjis,%82%a0

var sjisArray = new Uint8Array([0x82, 0xa0])
new TextDecoder("sjis").decode(sjisArray)


// バイナリデータの作成
var buffer = new ArrayBuffer(2)
var sjisArray = new Uint8Array(buffer)
sjisArray[0] = 0x82
sjisArray[1] = 0xa0

// blob
var blob = new Blob([buffer], {type:"text/plain;charset=SHIFT_JIS"})
var url = URL.createObjectURL(blob)
console.log("from blob", url)

// file
var file = new File([buffer], "foo.txt", {
  type: "text/plain;charset=SHIFT_JIS",
});
var url = URL.createObjectURL(file)
console.log("from file", url)