何时在Javascript中使用或不使用快捷方式变量

Question

这两个代码之间的最佳做法是什么？

1 - 使用变量隐藏复杂性并避免重复多次完整上下文

class FooController {
  myFunction(request, resolve, reject) {
    const lang = this.context.lang;
    const FooService = request.context.services.FooService;

    // use the variable lang multiple times (2 times to 10 times)
    FooService.getFoo().then(data => {
      data[lang] = "foo";
      resolve(data[lang]);
    }.catch(reject);
  }
}

2 - 重复多次变量的完整上下文

class FooController {
  myFunction(request, resolve, reject) {
    request.context.services.FooService.getFoo().then(data => {
      data[this.context.lang] = "foo";
      resolve(data[this.context.lang]);
    }.catch(reject);
  }
}