🔰code point

JS ⟩ value ⟩ primitive ⟩ String ⟩ Unicode ⟩ code point

numbers from U+0000 to U+10FFFF (17*2^16=1,114,112 total).

• usually represented using 4~6 hexadecimal digits.

• divided into 17 code planes. (2^16 code points each)

• every Unicode character is assigned a code point.

• UTF-16 transforms code points into

  • 1 code unit (scalar) or

  • 2 code units (surrogate pair).

🈯 synonyms： "Unicode character"

🗺️ 圖表

🧨 雷區

regex flag /u works on code points, not on grapheme clusters❗

⭐️ 重點

character encoding transforms code points into code units.

astral code points : U+10000 ~ U+10FFFF.

1,114,112 code points are available, but only 137,929 (as of May 2019) have assigned characters.

👥 相關

• escape sequence uses code points.

💈範例

• replit ⟩ code point

// code

📗

• Eloquent JavaScript ⟩ Strings & Character Codes

📘 手冊

• UTF-16 characters, code points, grapheme clusters
• String.prototype ⟩

  • .charCodeAt()
  • .codePointAt()
• String ⟩

  • .fromCodePoint()
  • .fromCharCode()