🔰code unit

🚧 under construction

JS ⟩ value ⟩ primitive ⟩ String ⟩ Unicode ⟩ encoding ⟩ UTF-16 ⟩ code unit

• UTF-16 code units are 16-bit unsigned integers. (0x0000 ~ 0xFFFF)

🗺️ 圖表

🧨 雷區

• string.codePointAt(index)

• string.slice(start, end)

• string[index]

uses index of code units, not characters❗

.split("") will split by UTF-16 code units and will separate surrogate pairs❗

By default, regular expressions work on code units, not actual characters❗

⭐️ 重點

(dangerous) use code units

• string.length

• string[index]

• string.charCodeAt(index)

(safe) use code points

• string iteration (for-of loop)

💈範例

• replit ⟩ code unit

// code

👥 相關

• Unicode

📗

• Eloquent JavaScript ⟩ Strings & Character Codes

📘 手冊

• UTF-16 characters, code points, grapheme clusters

• String.prototype ⟩

  • .charCodeAt()

  • .codePointAt()

• String ⟩

  • .fromCodePoint()

  • .fromCharCode()