hot-require.js

/**
 * Created by Surui on 2014/9/26.
 * E-Mail: surui.cc@gmail.com
 * github: https://github.com/rayosu/hot-require
 *
 */
var fs = require('fs');
var path = require('path');
var callsites = require('callsites');
var _cache = {};
var _copyProperty = function (target, source) {
    // proxy static function
    for (var key in source) {
        var property = source[key];
        if (typeof property == "function") {
            target[key] = function (_key) {
                return function () {
//                    console.log('invoke method: ' + _key);
                    return source[_key].apply(source, arguments);
                }
            }(key)
        } else {
            // invalid when target is prototype
            Object.defineProperty(target, key, {
                get: function (_key) {
                    return function () {
//                        console.log('getter: ' + _key);
                        return source[_key];
                    }
                }(key),
                set: function (_key) {
                    return function (value) {
//                        console.log('setter: ' + _key + ' ,value: ' + value);
                        source[_key] = value;
                    }
                }(key)
            })
        }
    }
    if (target.prototype && source.prototype) {
        // proxy prototype function
        _copyProperty(target.prototype, source.prototype);
    }
};
var _hasKey = function (obj) {
    for (var key in obj) {
        return true;
    }
    return false;
}
global._require = function (modulePath) {
    var callerPath = callsites()[1].getFileName();
    if (arguments.length == 2) {
        console.warn('since 0.0.7 you can use _require(\'path/to/your.js\') without __dirname in file: ' + callerPath);
        modulePath = arguments[1];
    }
    var _path = require.resolve(path.dirname(callerPath) + '/' + modulePath);
    if (_cache[_path]) return _cache[_path];

    var RealClass = require(_path);
    // constructor[execute property proxy handler when create Object]
    var Proxy = function () {
        var realObj = new RealClass(arguments);
        // proxy all realObj's property[field and method], use getter/setter on field, and use function proxy on function
        _copyProperty(this, realObj);
    };
    if (!_hasKey(RealClass)) {
        process.nextTick(function () {
            RealClass = require(_path);
            _copyProperty(Proxy, RealClass);
        });
    } else {
        // proxy static function
        _copyProperty(Proxy, RealClass);
    }
    // use 'watchFile' and not 'watch' to keep the callback invoke once one time when the file change.
    fs.watchFile(_path, function () {
        delete require.cache[_path];
        // update new js file
        RealClass = require(_path);
        _copyProperty(Proxy, RealClass);
        console.log('update js: ' + _path);
    });

    _cache[_path] = Proxy;
    return Proxy;
};