var a = {};

var namespace1 = {
  a: function(){},
  b: 2
}

var user = (function() {
  var _name = 'lee',
    _age = '25';
  return {
    getUserInfo: function() {
      return _name + ":" + _age;
    }
  };
})();

var getSingle = function(fn) {
  var result;
  return function() {
    return result || (result = fn.apply(this, arguments));
  };
};

// 测试
function testSingle(){}
getSingle(testSingle)() === getSingle(testSingle)();  // true

var lazyload = function() {
  console.log(1);
  lazyload = function() {
    console.log(2);
  }
  return lazyload();
}

lazyload();

var preload = (function() {
  console.log(1);
  preload = function() {
    console.log(2);
  };
  return preload;
})();

preload();