Create 26-property-pairs.js

js/26-property-pairs.js

@@ -0,0 +1,71 @@
+export default function compute() {
+
+let usedTogether = {};
+
+walkRules(ast.stylesheet.rules, rule => {
+	let props = new Set();
+
+	if (!rule.declarations) {
+		return;
+	}
+
+	let ruleProps = rule.declarations
+		// Ignore custom properties and prefixed ones. CP because they don't generalize
+		// and prefixed ones because they will trivially correlate with each other and the non-prefixed version
+		.filter(d => !d.property.startsWith("-"))
+		.map(d => d.property);
+
+	for (let prop of ruleProps) {
+		props.add(prop);
+	}
+
+	for (let prop of props) {
+		usedTogether[prop] = usedTogether[prop] || {};
+
+		for (let prop2 of props) {
+			if (prop === prop2) {
+				continue;
+			}
+
+			usedTogether[prop][prop2] = usedTogether[prop][prop2] || 0;
+			usedTogether[prop][prop2]++;
+		}
+	}
+}, {
+	// rules: r => Boolean(r.declarations),
+	not: {
+		type: "font-face"
+	}
+});
+
+let ret = {};
+
+// Now sort by usage count
+for (let prop in usedTogether) {
+	let obj = usedTogether[prop];
+
+	// Remove properties that are only used together once
+	for (let p in obj) {
+		if (obj[p] === 1) {
+			delete obj[p];
+		}
+		else {
+			let key = [prop, p].sort();
+			ret[key] = ret[key] || 0;
+			ret[key] += obj[p];
+		}
+	}
+
+	// let sortedEntries = Object.entries(obj).sort((a, b) => b[1] - a[1]);
+	//
+	// if (sortedEntries.length > 0) {
+	// 	usedTogether[prop] = Object.fromEntries(sortedEntries);
+	// }
+	// else {
+	// 	delete usedTogether[prop];
+	// }
+}
+
+return sortObject(ret);
+
+}