为什么在 javascript 中的 module.export 函数中分配了一个变量'this'

Question

我试图理解以下代码，这些代码取自在feathersjs应用程序中创建的服务。

// Initializes the `users` service on path `/users`
const createService = require('feathers-knex');
const createModel = require('../../models/users.model');
const hooks = require('./users.hooks');
const filters = require('./users.filters');
module.exports = function () {
  const app = this;
  const Model = createModel(app);
  const paginate = app.get('paginate');
  const options = {
    name: 'users',
    Model,
    paginate
  };
  // Initialize our service with any options it requires
  app.use('/users', createService(options));
  // Get our initialized service so that we can register hooks and filters
  const service = app.service('users');
  service.hooks(hooks);
  if (service.filter) {
    service.filter(filters);
  }
};

然后按如下方式导入此文件：

// many requires..
const feathers = require('feathers');
// more requires
const services = require('./services');
// other requires
const app = feathers();

有人可以解释一下这条线是什么吗

const app = this

在创建服务的代码中执行？

Answer 1

它将 this 的值分配给一个变量（嗯，一个常量），其名称比这更清楚地描述了该值。它旨在使代码更易于维护者理解。