Shift-JISなプロジェクトでGruntを使う。

converttosjis.js

module.exports = function (grunt) {
  var iconv = require('./lib/grunt-iconv-convertchar.js');
  grunt.registerMultiTask('converttosjis', 'Convert charcode from UTF-8 to Shift_Jis.', function () {
    iconv.convert(grunt, this, 'UTF-8', 'SHIFT_JIS');
  });
};

converttoutf8.js

module.exports = function (grunt) {
  var iconv = require('./lib/grunt-iconv-convertchar.js');
  grunt.registerMultiTask('converttoutf8', 'Convert charcode from Shift_Jis to UTF-8.', function () {
    iconv.convert(grunt, this, 'SHIFT_JIS', 'UTF-8');
  });
};

grunt-iconv-convertchar.js

exports.convert = function (grunt, self, charsetFrom, charsetTo) {
  var fs = require('fs');
  var exec = require('child_process').exec;
  function toArray (obj) {
    return (obj instanceof Array) ? obj : [obj];
  }

  function renameToUniq (orgName) {
    var destName = orgName;
    var i = 0;
    while (fs.existsSync(destName)) {
      destName = destName + '_' + i;
      i++;
    }
    fs.renameSync(orgName, destName);
    return destName;
  }

  var files = toArray(grunt.config(self.name)[self.target].src);
  var dests = toArray(grunt.config(self.name)[self.target].dest);

  var done = self.async();
  var doneCount = 0;
  for (var i=0, len=files.length; i<len; i++) {
    (function () {
      var src = files[i];
      var dest = dests[i];
      var isRenameSrc = false;
      if (src === dest) {
        src = renameToUniq(src);
        isRenameSrc = true;
      }
      var cmd = 'iconv -f ' + charsetFrom + ' -t ' + charsetTo + ' ' + src + '>' + dest;
      var child = exec(cmd, function (error, stdout, sderr) {
        if (error !== null) {
          grunt.log.writeln('exec error: ' + error);
        }
        grunt.log.writeln('File ' + dest + ' created.');

        if (isRenameSrc) {
          fs.unlinkSync(src);
        }
        doneCount++;
        if (doneCount === len) {
          done();
        }
      });
    })();
  }
};

Gruntfile.js

module.exports = function(grunt){

  'use strict';

  var path = require('path');
  var pkg = grunt.file.readJSON('package.json');
  
  grunt.initConfig({
    
    pkg: pkg,

    // Shift-JIS -> UTF8
    converttoutf8: {
      dist: {
        src: 'htdocs/js/hoge.js',
        dest: 'htdocs/js/hoge.js'
      }
    },

    // UTF8 -> Shift-JIS
    converttosjis: {
      dist: {
        src: 'htdocs/js/hoge.js',
        dest: 'htdocs/js/hoge.js'
      }
    }
    
  });
  
  // load tasks
  var taskNames;
  for(taskNames in pkg.devDependencies) {
    if(taskNames.substring(0, 6) == 'grunt-') {
      grunt.loadNpmTasks(taskNames);
    }
  }
  grunt.loadTasks('tasks');
  
  // regist tasks
  grunt.registerTask('default', ['converttoutf8', 'some', 'tasks', 'converttosjis']);

};

note.md

$ npm install iconv --save-dev

• Gruntfile.js
• htdocs/
  • js/hoge.js
• tasks/
  • converttosjis.js
  • converttoutf8.js
  • lib/grunt-iconv-convertchar.js