编码单元

Encoding & Standards

用于编码字符的最小位组合：UTF-8为8位，UTF-16为16位，UTF-32为32位。

A code unit is the fundamental building block of a Unicode encoding form. It's important to distinguish code units from code points — a single code point may require multiple code units depending on the encoding.

In UTF-8, a code unit is 8 bits (1 byte). The emoji 😀 requires 4 code units. In UTF-16, a code unit is 16 bits (2 bytes). The same emoji requires 2 code units (a surrogate pair). In UTF-32, it's 1 code unit (4 bytes).

Many programming language string APIs operate on code units rather than code points, which is why string length calculations can be confusing with emoji.

相关术语

UTF-16 UTF-16
每字符使用2或4个字节的可变长度Unicode编码方式，被JavaScript、Java和Windows内部使用。 UTF-32 UTF-32
每字符固定使用4个字节的Unicode编码方式，可直接映射到码位，但存储效率较低。 UTF-8 UTF-8
每字符使用1至4个字节的可变长度Unicode编码方式，是互联网上最主流的编码，被98%以上的网站采用。 代理对 代理对
用于表示U+FFFF以上字符的两个UTF-16编码单元组合，由高代理（U+D800-U+DBFF）和低代理（U+DC00-U+DFFF）构成。

相关工具

🔢 Unicode 查询 Unicode 查询
输入 U+1F600 等码位，获取表情符号、编码详情、UTF-8/16 字节和 HTML 实体。

相关故事

Unicode Lookup: Find Any Emoji by Code Point
Enter a Unicode code point like U+1F600 or paste an emoji to see its full encoding breakdown — UTF-8, UTF-16, HTML entities, and more.
How to Handle Emojis in JavaScript: Strings, Length, and Rendering
Learn how to work with emojis in JavaScript: string length pitfalls, Unicode code points, regex, grapheme segmentation, and React rendering tips.
Why string.length Lies: Grapheme Clusters and Emoji Length
Why string.length fails for emoji, what grapheme clusters are, and how to correctly count characters in JavaScript, Python, and more.
Emoji String Length Gotchas: Surrogate Pairs, Grapheme Clusters, and Byte Counts
Why emoji cause surprising string length results in Python, JavaScript, and Go — surrogate pairs, grapheme clusters, and how to count correctly.
Emoji Security: Homoglyphs, Spoofing, Invisible Characters, and Filtering
Security risks from emoji in user input: homoglyph spoofing, invisible Unicode characters, emoji in SQL/code injection, and how to filter and sanitize safely.
Emoji Regex Patterns: Matching Emojis in JavaScript and Python
Learn how to write reliable regex patterns to match emojis in JavaScript and Python, including ZWJ sequences, skin tones, and flags.