Add checkver tool.

README.md

@@ -45,6 +45,15 @@ Any more complicated setup should use a traditional rollup config file with plug
 [rollup-plugin-commonjs](https://github.com/rollup/rollup-plugin-commonjs).
 This package is for avoiding build system bloat in simpler cases.
 
+For testing packages with old Node.js versions (lack of modern JavaScript features can resemble old mobile browsers),
+it can be helpful to run `rollup` conditionally in package scripts using the included `checkver` tool:
+
+```json
+{
+  "prepublish": "(checkver ge 5.0.0 && rollup -c)"
+}
+```
+
 # License
 
 [The MIT License](https://raw.githubusercontent.com/charto/autoroll/master/LICENSE)

checkver

@@ -0,0 +1,32 @@
+#!/usr/bin/env node
+
+var op = process.argv[2].match(/^([gl])([te])$/);
+var wanted = (process.argv[3] || '').split('.');
+var version = process.versions.node.split('.');
+
+if(!op || wanted.length != 3) {
+	console.log([
+		'usage:',
+		process.argv[0].replace(/.*\//, ''),
+		process.argv[1].replace(/.*\//, ''),
+		'op',
+		'x.y.z'
+	].join(' '));
+
+	console.log('\nCompare Node.js version.');
+	console.log('Following op codes determine whether it must be:\n');
+
+	console.log('\tgt\tGreater than x.y.z.');
+	console.log('\tge\tGreater than or equal to x.y.z.');
+	console.log('\tlt\tLess than x.y.z.');
+	console.log('\tle\tLess than or equal to x.y.z.');
+
+	process.exit(1);
+}
+
+for(var i = 0; i < 3; ++i) {
+	if(+version[i] > +wanted[i]) process.exit(+(op[1] != 'g'));
+	if(+version[i] < +wanted[i]) process.exit(+(op[1] == 'g'));
+}
+
+process.exit(+(op[2] != 'e'));

package.json

@@ -3,6 +3,9 @@
   "version": "0.1.0",
   "description": "Rollup autoconfigurator",
   "main": "index.js",
+  "bin": {
+    "checkver": "checkver"
+  },
   "author": "Juha Järvi",
   "license": "MIT",
   "repository": {
@@ -14,6 +17,8 @@
   },
   "homepage": "https://github.com/charto/autoroll#readme",
   "keywords": [
+    "loader",
+    "module",
     "package",
     "rollup"
   ]