Node.js - Handle body-parser invalid JSON error

One option is to add a custom error handler middleware and add a check to catch JSON parsing errors like that one:

app.use(require('body-parser').json()); app.use(require('body-parser').urlencoded({ extended: true }));...app.use((err, req, res, next) => {    // This check makes sure this is a JSON parsing issue, but it might be    // coming from any middleware, not just body-parser:    if (err instanceof SyntaxError && err.status === 400 && 'body' in err) {        console.error(err);        return res.sendStatus(400); // Bad request    }    next();});

Another option is to wrap body-parser's middleware to catch errors coming only from there:

const bodyParser = require('body-parser');app.use((req, res, next) => {    bodyParser.json()(req, res, err => {        if (err) {            console.error(err);            return res.sendStatus(400); // Bad request        }        next();    });});

Or if you want to reuse this functionality to catch different errors from different middlewares, you can do:

function handleError(middleware, errorHandler) {    middleware(req, res, err => err ? errorHandler(err, req, res, next) : next());}const bodyParser = require('body-parser');app.use(handleError(bodyParser.json(), (err, req, res, next) => {    if (err) {        console.error(err);        return res.sendStatus(400); // Bad request    }    next();}));

As of Express 4.16.0 - Release date: 2017-09-28 you can catch different errors from different middlewares splitting the error handler into a different function without using Bodyparser as it is deprecated.

const app = express();function handleError(middleware, req, res, next) {  middleware(req, res, (err) => {    if (err) {      console.error(err);      return res.sendStatus(400); // Bad request    }    next();  });}app.use((req, res, next) => {  handleError(express.json(), req, res, next);});

Notice in the code as of Express 4.16.0 and higher that express:

 app.use(express.json()); // Without middleware error handling.

replaces bodyParser:

 app.use(bodyParser.json()); // Without middleware error handling.

Add an error handler and then customize the behavior of the default way to handle that erorr, the default will be to crash as you describe.

app.use((err, req, res, callback) => {  // todo: implement error handling logic and return an appropriate response  console.error(err)  res.send(500)  callback()})