node.js 动态执行脚本

var Script = process.binding('evals').NodeScript;
var runInThisContext = Script.runInThisContext;
 
 NativeModule.wrap = function(script) {
  return NativeModule.wrapper[0] + script + NativeModule.wrapper[1];
 };
 
 NativeModule.wrapper = [
  '(function (exports, require, module, __filename, __dirname) { ',
  '\n});'
 ];
 
 NativeModule.prototype.compile = function() {
  var source = NativeModule.getSource(this.id);
  source = NativeModule.wrap(source);
 
  var fn = runInThisContext(source, this.filename, true);
  fn(this.exports, NativeModule.require, this, this.filename);
 
  this.loaded = true;
 };

var Script = process.binding('evals').NodeScript;
console.log(Script)
/**
{ [Function: NodeScript]
 createContext: [Function],
 runInContext: [Function],
 runInThisContext: [Function],
 runInNewContext: [Function] }
 
*/
console.log(require('vm'))
{ Script: 
  { [Function: NodeScript]
   createContext: [Function],
   runInContext: [Function],
   runInThisContext: [Function],
   runInNewContext: [Function] },
 createScript: [Function],
 createContext: [Function],
 runInContext: [Function],
 runInThisContext: [Function],
 runInNewContext: [Function] }

var vm = require('vm'),
 code = 'var square = n * n;',
 fn = new Function('n', code),
 script = vm.createScript(code),
 sandbox;
 
n = 5;
sandbox = { n: n };
 
benchmark = function(title, funk) {
 var end, i, start;
 start = new Date;
 for (i = 0; i < 5000; i++) {
  funk();
 }
 end = new Date;
 console.log(title + ': ' + (end - start) + 'ms');
}
 
var ctx = vm.createContext(sandbox);
benchmark('vm.runInThisContext',   function() { vm.runInThisContext(code); });
benchmark('vm.runInNewContext',   function() { vm.runInNewContext(code, sandbox); });
benchmark('script.runInThisContext', function() { script.runInThisContext(); });
benchmark('script.runInNewContext', function() { script.runInNewContext(sandbox); });
benchmark('script.runInContext', function() { script.runInContext(ctx); });
benchmark('fn',           function() { fn(n); });
/**
vm.runInThisContext: 212ms
vm.runInNewContext: 2222ms
script.runInThisContext: 6ms
script.runInNewContext: 1876ms
script.runInContext: 44ms
fn: 0ms
 
*/