Express.js API Message Standardization with JSend

By following shared and consistent format on how JSON should response, it promotes unity with less argument between backend developers and frontend developers / designers, as everyone following the shared conventions.

What is JSend?

JSend is a simple yet well structured specification created by Omniti that lays down rules for how JSON message response from web API should be formatted. It focuses on application level messaging which make it ideal for REST APIs.

How to response a JSend-compliant message using Express?

A simple Express app response with a succesful JSend-compliant message:

var express = require('express')
  , app = express()
  , PORT = 3000;

app.get('/success', function (req, res){
  res.json({
      "status":"success",
      "data": { 
          "post" : { "id" : 1, "title" : "A blog post", "body" : "Some useful content" }
        } 
      });
});

app.listen(PORT, function(){
    console.log('Server listening on port ' + PORT);
})

Run the following command on your terminal:

curl http://localhost:3000/success

It should return with a successful JSend-compliant response:

{"status":"success","data":{"post":{"id":1,"title":"A blog post","body":"Some useful content"}}}

Introducing JSendie Middleware

To prevent from writing the JSend-compliant response repeatedly for each route, you can use JSendie middleware.

Install JSendie middleware:

npm install jsendie --save

Setup the middleware in your Express app before any routes:

var express = require('express')
  , jsendie = require('jsendie')
  , app = express()
  , PORT = 3000;

// remember to use it before any routes
app.use(jsendie());

app.get('/success', function (req, res){
  res.success({
    "post" : { "id" : 1, "title" : "A blog post", "body" : "Some useful content" }
  });
});

app.listen(PORT, function(){
    console.log('Server listening on port ' + PORT);
})

Run the following command on your terminal:

curl http://localhost:3000/success

Should return the same successful JSend-compliant response:

{"status":"success","data":{"post":{"id":1,"title":"A blog post","body":"Some useful content"}}}

Read more on how to use methods provides by JSendie to response success, fail, and error JSend-compliant message.