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type: slide
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## console.log("🤦🏼‍♂️".length)
- 2024.03.05 / bob chang
- [2023 年每个软件开发者都必须知道的关于 Unicode 的最基本的知识（仍然不准找借口！）](https://blog.xinshijiededa.men/unicode/#user-content-fnref-touche)

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## agenda
1. 介紹 Unicode
2. 介紹 UTF-8
3. What’s "🤦🏼‍♂️".length?
4. "Å" !== "Å" !== "Å"？

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### Unicode == character ⟷ code point.
* The Latin letter `A` is assigned the number `65`.
* The Arabic Letter Seen `س` is `1587`.
* The Katakana Letter Tu `ツ` is `12484`
* The Musical Symbol G Clef `𝄞` is `119070`.
* `💩` is `128169` (`0x1F4A9`).

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- the largest is 0x10FFFF. 全部約 110 萬個空間
- https://symbl.cc/en/unicode/table/

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### What’s Private Use?
- 这些码位是为应用程序开发人员保留的，Unicode 自己永远不会定义它们
- 例如，Unicode 中没有苹果 logo 的位置，因此 Apple 将其放在私用区块中的 U+F8FF
- 在任何其他系統中，它都将呈现为缺失的字形 `􀣺`，但在 macOS 附带的字体中，你就可以看到 
- `option`+`shift`+`k` = 
- `control` +`command`+`space` → 叫出符號視窗

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### UTF-8 is a variable-length encoding
- A code point might be encoded as a sequence of one to four bytes.

| | code | UTF-8 | UTF-16 | UTF-32 |
|---|---------|---------|---|---|
|`A`| `0041` | `41` | `0041` | `00000041` |
|`樂`| `6A02` | `E6A882` | `6A02` | `00006A02` |
|`💩`| `1F4A9` | `F09F92A9` | `D83DDCA9` | `0001F4A9` |

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### What’s "🤦🏼‍♂️".length?


- 🤦🏼‍♂️ → U+1F926 U+1F3FB U+200D U+2642 U+FE0F
- https://hsivonen.fi/string-length/

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# "Å" !== "Å" !== "Å"？


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### Before comparing strings, normalize!

<!-- https://stackoverflow.com/a/63013732 -->

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### Why does `toLowerCase()` accepts Locale as an argument?

var en_US = Locale.of("en", "US");
var tr = Locale.of("tr");

"I".toLowerCase(en_US); // => "i"
"I".toLowerCase(tr); // => "ı"

"i".toUpperCase(en_US); // => "I"
"i".toUpperCase(tr); // => "İ"'

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### 規則每年都在變

- Unicode 每年 release 新的版本
- 這是為什麼我們每年都有新的 emoji 可以用


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# 🧋🧋🧋

- 算字數，要注意 ⚠️
- 字串比對，要注意 ⚠️

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- [歡迎來到字嗨！](https://zi-hi.com)
- [Taiwan Emoji Project](https://www.shinylee.com/project/taiwan-emoji-project)
- [emojikitchen](https://emojikitchen.dev)