var benchmarking

var-benchmarking

function benchmark(func){
  var s = Date.now();
  var obj = {a: 1, b: 2};
  Array(10000).join(' ').split('').forEach(function(){
      func('c = a * b', obj)
      func('c', obj)
  });
  var e = Date.now();

  console.log( 'total cost:' + (e - s));
}

var cache1 = {};
function evaltest(expression, obj) {
  if (!cache1[expression]) {
    cache1[expression] = evalcompile(expression);
  }
  return cache1[expression](obj);
}

function evalcompile(expression) {
  return function(obj) {
    var x = null;
    try {
      with (obj) {
         x = eval('(' + expression + ')');
      }
    } finally {
      return x;
    }
  };
}

var cache = {};
function compiletest(expression, obj) {
  if (!cache[expression]) {
    cache[expression] = compile(expression);
  }
  return cache[expression](obj);
}
var      re_vars = /(['"\/]).*?[^\\]\1|\.\w*|\w*:|\b(?:(?:new|typeof|in|instanceof) |(?:this|true|false|null|undefined)\b|function *\()|([a-z_$]\w*)/gi;

  function wrap(s, nonull) {
    s = s.trim()
    return !s ? 'void 0' : '(function(v){try{\n v='

        // prefix vars (name => data.name)
        + (s.replace(re_vars, function(s, _, v) { return v ? 'd.'+ v : s })

          // break the expression if its empty (resulting in undefined value)
          || 'x')

      + '\n}finally{\nreturn v;'

      + '}}).call(d)'
  }

function compile(expression) {
  return new Function('d', 'return ' + wrap(expression));
}


benchmark(evaltest);
benchmark(compiletest);