Zero-Width Joiner U+200D

The zero-width joiner (ZWJ, U+200D) is an invisible Unicode character that forces adjacent characters to join. Family, profession and gendered emoji are several emoji combined into one with ZWJ characters between them. In Arabic, Persian, Devanagari and other complex scripts, ZWJ forces letters to connect where they would otherwise appear in isolated forms.

How ZWJ Creates Emoji

If your device supports the combination, it renders one emoji instead of the parts.

Examples of ZWJ Sequences

Woman Technologist is three code points: Woman (U+1F469) + ZWJ (U+200D) + Laptop (U+1F4BB). A family emoji can be seven or more.

What Happens When ZWJ Sequences Aren't Supported

A device that doesn't support a sequence shows the component emoji side by side. That's why you sometimes get odd emoji combinations in messages: the sender's device combined them, yours didn't.

Common Uses

• Composite emoji. Family groups, professions, gendered variants and accessibility emoji all use ZWJ sequences (skin tones use separate modifier characters).
• Connected letter forms in Arabic and Persian. Letters change shape by position in a word. ZWJ forces the connected form even at word boundaries.
• Devanagari and Indic ligatures. ZWJ creates specific conjunct forms in Hindi, Sanskrit and other scripts.
• South Asian text layout. Bengali, Tamil, Telugu and other scripts use it to control how characters combine.

How to Type

ZWJ in Arabic and Persian Text

ZWJ was created for complex scripts, not emoji. Arabic and Persian letters have up to four forms: isolated, initial (start of word), medial (middle) and final (end). Adjacent letters decide which form appears.

ZWJ forces the connected form where a letter would normally stand alone. Persian connection rules differ from Arabic, so Persian writers need this fine control. For example, ZWJ after the last letter of a word forces its medial or initial form instead of its final form, which can change the meaning or visual style.

Technical Details

• Category: Format (Cf).
• Width: Zero. No visible glyph.
• Line breaking: The Unicode Line Breaking Algorithm does not break directly after a ZWJ, so a ZWJ sequence stays on one line.
• Joining behavior: The characters on either side use their connected forms, as if they were adjacent letters in one word.
• Emoji behavior: Between two emoji, it makes the renderer look up the combined sequence in its emoji table.

Match ZWJ in regular expressions with \u200D.

Security Considerations

• String length confusion. One visible emoji can be 7+ code points, which breaks code-point counts.
• Text comparison issues. An exact match on a person emoji won't match its gendered or skin-toned version, since those are different sequences. Substring searches can also find the base emoji inside a longer sequence.
• Input validation bypass. Character limits can be bypassed if they count visual characters differently from code points.

Counting Characters in ZWJ Emoji

For character counters, length limits or truncation, count grapheme clusters with Intl.Segmenter or a grapheme-cluster library:

// JavaScript: count visual characters (grapheme clusters)const segmenter = new Intl.Segmenter('en', { granularity: 'grapheme' });const count = [...segmenter.segment(text)].length;

How ZWJ Differs from Similar Characters

ZWJ and ZWNJ are direct opposites. ZWNJ prevents connections in Persian and Arabic text.