Fix width calculation for minimally-qualified emoji sequences

Fixes #67

Author: sindresorhus

index.js

@@ -7,7 +7,8 @@ Logic:
 - Width rules:
 	1. Skip non-printing clusters (Default_Ignorable, Control, pure Mark, lone Surrogates). Tabs are ignored by design.
 	2. RGI emoji clusters (\p{RGI_Emoji}) are double-width.
-	3. Otherwise use East Asian Width of the cluster’s first visible code point, and add widths for trailing Halfwidth/Fullwidth Forms within the same cluster (e.g., dakuten/handakuten/prolonged sound mark).
+	3. Minimally-qualified/unqualified emoji clusters (ZWJ sequences with 2+ Extended_Pictographic, or keycap sequences) are double-width.
+	4. Otherwise use East Asian Width of the cluster's first visible code point, and add widths for trailing Halfwidth/Fullwidth Forms within the same cluster (e.g., dakuten/handakuten/prolonged sound mark).
 */
 
 const segmenter = new Intl.Segmenter();
@@ -21,6 +22,30 @@ const leadingNonPrintingRegex = /^[\p{Default_Ignorable_Code_Point}\p{Control}\p
 // RGI emoji sequences
 const rgiEmojiRegex = /^\p{RGI_Emoji}$/v;
 
+// Detect minimally-qualified/unqualified emoji clusters (missing VS16)
+// - ZWJ sequences with 2+ Extended_Pictographic (e.g., ❤‍🔥, 🏳‍🌈, ⛹‍♂)
+// - Keycap sequences (e.g., #⃣, 0⃣)
+const zwjRegex = /\u200D/;
+const validKeycapRegex = /^[\d#*].*\u20E3/;
+const extendedPictographicRegex = /\p{Extended_Pictographic}/gu;
+
+function isDoubleWidthEmojiCluster(segment) {
+	// Keycap sequences with valid base (0-9, #, *)
+	if (validKeycapRegex.test(segment)) {
+		return true;
+	}
+
+	// ZWJ sequences with 2+ Extended_Pictographic
+	if (zwjRegex.test(segment)) {
+		const matches = segment.match(extendedPictographicRegex);
+		if (matches && matches.length >= 2) {
+			return true;
+		}
+	}
+
+	return false;
+}
+
 function baseVisible(segment) {
 	return segment.replace(leadingNonPrintingRegex, '');
 }
@@ -72,7 +97,7 @@ export default function stringWidth(input, options = {}) {
 		}
 
 		// Emoji width logic
-		if (rgiEmojiRegex.test(segment)) {
+		if (rgiEmojiRegex.test(segment) || isDoubleWidthEmojiCluster(segment)) {
 			width += 2;
 			continue;
 		}

test.js

@@ -249,3 +249,23 @@ test('digit zero as plain text (not emoji)', macro, '0', 1);
 test('digit one as plain text', macro, '1', 1);
 test('asterisk as plain text', macro, '*', 1);
 test('hash as plain text', macro, '#', 1);
+
+// Minimally-qualified/unqualified emoji sequences
+// These are emoji sequences missing VS16 but should still be width 2
+test('heart on fire (MQ)', macro, '\u2764\u200D\u{1F525}', 2); // ❤‍🔥
+test('rainbow flag (MQ)', macro, '\u{1F3F3}\u200D\u{1F308}', 2); // 🏳‍🌈
+test('transgender flag (MQ)', macro, '\u{1F3F3}\u200D\u26A7', 2); // 🏳‍⚧
+test('broken chain (MQ)', macro, '\u26D3\u200D\u{1F4A5}', 2); // ⛓‍💥
+test('eye in speech bubble (MQ)', macro, '\u{1F441}\u200D\u{1F5E8}', 2); // 👁‍🗨
+test('man bouncing ball (MQ)', macro, '\u26F9\u200D\u2642', 2); // ⛹‍♂
+test('woman bouncing ball (MQ)', macro, '\u26F9\u200D\u2640', 2); // ⛹‍♀
+test('man detective (MQ)', macro, '\u{1F575}\u200D\u2642', 2); // 🕵‍♂
+test('woman detective (MQ)', macro, '\u{1F575}\u200D\u2640', 2); // 🕵‍♀
+
+// Unqualified keycap sequences (missing VS16)
+test('keycap # (UQ)', macro, '#\u20E3', 2); // #⃣
+test('keycap 0 (UQ)', macro, '0\u20E3', 2); // 0⃣
+test('keycap * (UQ)', macro, '*\u20E3', 2); // *⃣
+
+// Ensure invalid keycap sequences don't match
+test('phone + keycap (invalid)', macro, '\u260E\uFE0F\u20E3', 1); // Not a valid keycap base