Create 05-specificity.js

Rel #5

js/05-specificity.js

@@ -0,0 +1,36 @@
+export default function compute() {
+
+let ret = {
+	selectorCount: 0,
+	ruleCount: 0,
+	specificityCount: {},
+	maxSpecifity: [0, 0, 0]
+};
+
+let ss = [0, 0, 0];
+
+walkRules(ast, rule => {
+	ret.ruleCount++;
+
+	for (let selector of rule.selectors) {
+		ret.selectorCount++;
+		let s = parsel.specificity(selector);
+		ss = ss.map((a, i) => a + s[i]);
+		let max = Math.max(...s);
+
+		incrementByKey(ret.specificityCount, max <= 5? s + "" : "higher");
+
+		let base = Math.max(...ret.maxSpecifity, ...s);
+		if (parsel.specificityToNumber(s, base) > parsel.specificityToNumber(ret.maxSpecifity, base)) {
+			ret.maxSpecifity = s;
+			ret.maxSpecifitySelector = selector;
+		}
+	}
+}, {type: "rule"});
+
+ret.selectorsPerRule = ret.selectorCount / ret.ruleCount;
+ret.avgSpecificity = ss.map(s => s / ret.selectorCount);
+
+return ret;
+
+}