After reading this guide you will know:
Middleware is a function that gets executed before command’s .run() method. You can insert multiple middleware functions. Each function is invoked with a callback, that should be called when the work is done. All middleware functions should be defined separately in middleware/ directory of the project. For example:
1 2 3 4 5 | - index.js - commands/ - middleware/ - auth.js - check.js |
And each file in middleware/ directory looks like that:
1 2 3 4 5 | module.exports = function middlewareName (next) { // do some work next(); }; |
If middleware determined that the process should shutdown, then it should just throw an error and its message will be displayed in the console:
1 2 3 | module.exports = function auth (next) { throw new Error('Authentication failed!'); } |