michel-zimmer · November 16, 2016 09:29 · Nov 16, 2016
diff --git a/lpd.js b/lpd.js
@@ -0,0 +1,38 @@
+#!/usr/bin/env node
+
+const ignorecase = true;
+const include = "abcdefghijklmnopqrstuvwxyz";
+
+function lpd(data) {
+  // prepare
+  let distribution = {};
+  let sum = 0;
+  include.split('').forEach(c => distribution[c] = 0);
+
+  // ignore case
+  if (ignorecase) {
+    data = data.toLowerCase();
+  }
+
+  // count
+  data.split('').forEach(c => {
+    if (include.indexOf(c) >= 0) {
+      distribution[c]++;
+      sum++;
+    }
+  });
+
+  // calculate and round percentage
+  include.split('').forEach(c => distribution[c] = Math.round(distribution[c] * 10000 / sum) / 100);
+
+  return distribution;
+}
+
+// use stdin and stout when called directly
+if (require.main === module) {
+  let data = "";
+  process.openStdin().on('data', (chunk) => data += chunk).on('end', () => console.log(JSON.stringify(lpd(data), null, 2)));
+} else {
+  // otherwise export as module
+  exports = lpd;
+}