build: add version script for npm version releases

Author: dougwilson

package.json

@@ -41,6 +41,7 @@
     "lint": "eslint .",
     "test": "node test/run.js",
     "test-ci": "nyc --reporter=text npm test",
-    "test-cov": "nyc --reporter=html --reporter=text npm test"
+    "test-cov": "nyc --reporter=html --reporter=text npm test",
+    "version": "node tool/version-changes.js"
   }
 }

tool/version-changes.js

@@ -0,0 +1,35 @@
+#!/usr/bin/env node
+var fs   = require('fs');
+var path = require('path');
+
+var changesFilePath     = path.join(__dirname, '..', 'Changes.md');
+var changesFileContents = fs.readFileSync(changesFilePath, 'utf-8');
+var changesHeadRegexp   = /^## HEAD$/m;
+var date                = getLocaleDate();
+var version             = process.env.npm_package_version;
+
+if (!changesHeadRegexp.test(changesFileContents)) {
+  console.error('Changes.md missing version marker.');
+  process.exit(1);
+}
+
+fs.writeFileSync(changesFilePath,
+  changesFileContents.replace(changesHeadRegexp, '## v' + version + ' (' + date + ')'));
+
+function getLocaleDate() {
+  var now = new Date();
+
+  return zeroPad(now.getFullYear(), 4) + '-' +
+    zeroPad(now.getMonth() + 1, 2) + '-' +
+    zeroPad(now.getDate(), 2);
+}
+
+function zeroPad(number, length) {
+  number = number.toString();
+
+  while (number.length < length) {
+    number = '0' + number;
+  }
+
+  return number;
+}