code: function modInitFactoryInvoker(id) {
          var mod = modModules[id];
          var invoking;
  
          mod.invokeFactory = invokeFactory;
  
          /**
           * 初始化模块
           *
           * @inner
           */
          function invokeFactory() {
              if (invoking || mod.state !== MODULE_PREPARED) {
                  return;
              }
  
              invoking = 1;
  
              // 拼接factory invoke所需的arguments
              var factoryReady = 1;
              each(
                  mod.factoryDeps,
                  function (dep) {
                      var depId = dep.absId;
  
                      if (!BUILDIN_MODULE[depId]) {
                          modTryInvokeFactory(depId);
                          return (factoryReady = modIs(depId, MODULE_DEFINED));
                      }
                  }
              );
  
              if (factoryReady) {
                  try {
                      // 调用factory函数初始化module
                      var factory = mod.factory;
                      var exports = typeof factory === 'function'
                          ? factory.apply(global, modGetModulesExports(
                                  mod.factoryDeps,
                                  {
                                      require: mod.require,
                                      exports: mod.exports,
                                      module: mod
                                  }
                              ))
                          : factory;
  
                      if (exports != null) {
                          mod.exports = exports;
                      }
  
                      mod.invokeFactory = null;
                  }
                  catch (ex) {
                      mod.hang = 1;
                      throw ex;
                  }
  
                  // 完成define
                  // 不放在try里，避免后续的运行错误被这里吞掉
                  modDefined(id);
              }
          }
      }
docs: 初始化模块定义时所需的factory执行器
  
  @inner
  @param {string} id 模块id