Initial data commit

Task/Entropy/JavaScript/entropy-2.js

@@ -0,0 +1,15 @@
+const entropy = (s) => {
+  const split = s.split('');
+  const counter = {};
+  split.forEach(ch => {
+    if (!counter[ch]) counter[ch] = 1;
+    else counter[ch]++;
+  });
+
+
+  const lengthf = s.length * 1.0;
+  const counts = Object.values(counter);
+  return -1 * counts
+    .map(count => count / lengthf * Math.log2(count / lengthf))
+    .reduce((a, b) => a + b);
+};