# Title: Code Style Guide

Developers are advised to use egg-init --type=simple showcase to generate and observe the recommended project structure and configuration.

# Classify

// old style
module.exports = app => {
class UserService extends app.Service {
async list() {
return await this.ctx.curl('https://eggjs.org');
}
}
return UserService;
};

change to:

const Service = require('egg').Service;
class UserService extends Service {
async list() {
return await this.ctx.curl('https://eggjs.org');
}
}
module.exports = UserService;

Additionally, the framework developer needs to change the syntax as follows, otherwise the application developer will have problems customizing base classes such as Service:

const egg = require('egg');

module.exports = Object.assign(egg, {
Application: class MyApplication extends egg.Application {
// ...
}
// ...
});

# Private properties & Lazy Initialization

  • Private properties are mounted with Symbol.
  • The description of Symbol follows the rules of jsdoc, describing the mapped class name + attribute name.
  • Delayed initialization.
// app/extend/application.js
const CACHE = Symbol('Application#cache');
const CacheManager = require('../../lib/cache_manager');

module.exports = {
get cache() {
if (!this[CACHE]) {
this[CACHE] = new CacheManager(this);
}
return this[CACHE];
}
};