为什么在JavaScript的module.export函数中为变量分配了“ this”

Question

我试图理解以下代码，这些代码取自于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);
  }
};

然后按以下方式导入该文件：

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

有人可以解释一下线路是什么

const app = this

在创建服务的代码中做什么？

Answer 1

它的值赋给this给一个变量（当然，常数）与更清楚地描述了比这确实值的名称。 它旨在使维护人员更容易理解代码。