add grunt, see more in README.md about how to use intstall and use grunt

.gitignore

@@ -22,3 +22,6 @@ _site
 ehthumbs.db
 Icon?
 Thumbs.db
+#  nodejs packages   #
+######################
+node_modules

.jshintrc

@@ -0,0 +1,3 @@
+{
+    "asi": true
+}

GruntFile.js

@@ -0,0 +1,87 @@
+module.exports = function(grunt) {
+
+    //Project configuration.
+    grunt.initConfig({
+        pkg: grunt.file.readJSON('package.json'),
+        concat: {
+            options: {
+                separator: ''
+            },
+            dist: {
+                src: [
+                     'src/intro.js',
+                     'src/core.js',
+                     'src/tooltip.js',
+                     'src/utils.js',
+                     'src/models/axis.js',
+                     'src/models/historicalBar.js',
+                     'src/models/bullet.js',
+                     'src/models/bulletChart.js',
+                     'src/models/cumulativeLineChart.js',
+                     'src/models/discreteBar.js',
+                     'src/models/discreteBarChart.js',
+                     'src/models/distribution.js',
+                     'src/models/indentedTree.js',
+                     'src/models/legend.js',
+                     'src/models/line.js',
+                     'src/models/lineChart.js',
+                     'src/models/linePlusBarChart.js',
+                     'src/models/lineWithFocusChart.js',
+                     'src/models/linePlusBarWithFocusChart.js',
+                     'src/models/multiBar.js',
+                     'src/models/multiBarChart.js',
+                     'src/models/multiBarHorizontal.js',
+                     'src/models/multiBarHorizontalChart.js',
+                     'src/models/multiChart.js',
+                     'src/models/ohlcBar.js',
+                     'src/models/pie.js',
+                     'src/models/pieChart.js',
+                     'src/models/scatter.js',
+                     'src/models/scatterChart.js',
+                     'src/models/scatterPlusLineChart.js',
+                     'src/models/sparkline.js',
+                     'src/models/sparklinePlus.js',
+                     'src/models/stackedArea.js',
+                     'src/models/stackedAreaChart.js',
+                     'src/outro.js'
+                     ],
+                dest: 'nv.d3.js'
+            }
+        },
+        uglify: {
+            options: {
+                banner: '/*! <%= pkg.name %> - v<%= pkg.version %> - ' +
+                    '<%= grunt.template.today("yyyy-mm-dd") %> */'
+            },
+            js: {
+                files: {
+                    'nv.d3.min.js': ['nv.d3.js']
+                }
+            }
+        },
+        jshint: {
+            foo: {
+                src: "src/**/*.js"
+            },
+            options: {
+                jshintrc: '.jshintrc'
+            }
+        },
+        watch: {
+            js: {
+                files: ["src/**/*.js"],
+                tasks: ['concat']
+            }
+        },
+
+    });
+
+    grunt.loadNpmTasks('grunt-contrib-watch');
+    grunt.loadNpmTasks('grunt-contrib-concat');
+    grunt.loadNpmTasks('grunt-contrib-jshint');
+    grunt.loadNpmTasks('grunt-contrib-uglify');
+
+    grunt.registerTask('default', ['concat']);
+    grunt.registerTask('production', ['concat', 'uglify']);
+    grunt.registerTask('lint', ['jshint']);
+};

README.md

@@ -41,6 +41,19 @@ fork's root directory will rebuild both `nv.d3.js` and `nv.d3.min.js`.
 
 Without UglifyJS, you won't get the minified version when running make.
 
+## use grunt
+
+You can use grunt insteadof makefile to build js file. See more about [grunt](http://gruntjs.com/).
+***[Nodejs](http://nodejs.org/) must be installed before you can use grunt.***
+Run `npm install` in root dir to install grunt and it's dependencies.
+
+Then, you can use these commands:
+
+    grunt # build nv.d3.js
+    grunt production # build nv.d3.js and nv.d3.min.js
+    grunt watch # watch file changes in src/, and rebuild nv.d3.js, it's very helpful when delevop nvd3
+    grunt lint # run jshint on src/**/*.js
+
 **We ask that you DO NOT minify pull requests... 
 If you need to minify please build pull request in separate branch, and
 merge and minify in your master.