refactor: better perf support

this should finish what @stevemao said in left-pad#11

package.json

@@ -5,10 +5,11 @@
   "main": "index.js",
   "scripts": {
     "test": "node test",
-    "bench": "node perf_test.js"
+    "bench": "node perf/perf.js"
   },
   "devDependencies": {
     "benchmark": "^2.1.0",
+    "microtime": "^2.0.0",
     "tape": "*"
   },
   "keywords": [

perf/es6Repeat.js

@@ -0,0 +1,19 @@
+'use strict';
+
+module.exports = function leftpadEs6Repeat (str, len, ch) {
+  var l;
+
+  str = String(str);
+  l = len - str.length;
+
+  if (!ch && ch !== 0) {
+    ch = ' ';
+  }
+
+  if (l > 0) {
+    return ch.repeat(l) + str;
+  }
+
+  return str;
+
+};

perf/original.js

@@ -0,0 +1,20 @@
+'use strict';
+
+module.exports = function leftpadOriginal (str, len, ch) {
+  str = String(str);
+
+  var i = -1;
+
+  if (!ch && ch !== 0) {
+    ch = ' ';
+  }
+
+  len = len - str.length;
+
+  while (++i < len) {
+    str = ch + str;
+  }
+
+  return str;
+}
+

perf/perf.js

@@ -0,0 +1,38 @@
+'use strict';
+
+
+var leftpadOriginal = require('./original');
+var leftpadEs6Repeat = require('./es6Repeat');
+var leftpadBitOps = require('../');
+
+var Benchmark = require('benchmark');
+
+var str = "abcd"
+var len = 100;
+
+function buildSuite (note, methods, parameters) {
+  console.log(note);
+  var newSuite = new Benchmark.Suite;
+
+  Object.keys(methods).forEach(function (name) {
+    newSuite.add(name, function () {
+      methods[name].apply(null, parameters);
+    });
+  });
+  newSuite.on('cycle', function (event) {
+    console.log(String(event.target));
+  }).on('complete', function () {
+    console.log('Fastest is ' + this.filter('fastest').map('name'));
+  });
+
+  return newSuite;
+}
+
+var methods = {
+  'Long - Original': leftpadOriginal,
+  'Long - ES6 Repeat': leftpadEs6Repeat,
+  'Long - Bit Operation': leftpadBitOps
+};
+
+buildSuite('-> len = 100', methods, ['abcd', 100, ' ']).run();
+buildSuite('-> len = 10', methods, ['abcd', 10,  ' ']).run();