[Node.js] Exception Handling in Node.js Express

Thu, 10 Mar 2016 09:30:18 +0000

Since Node.js is non-blocking, single-process, and single-threaded, once an exception is thrown, the entire service stops, making it very unstable. Here are the solutions:

Make the program robust: Wrap all potentially exception-prone areas with try { } catch(){ }.
Express error handling mechanism: As a commonly used Node.js framework, Express has its own error handling mechanism.

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// Express' errorHandler
function errorHandler(err, req, res, next) {
 console.error(err.stack);
 res.status(500).send('Something broke!');
}
app.use(errorHandler);

Use the domain module: First install the domain module with npm install domain

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// Domain exception handling
const domain = require('domain');

app.use(function(req, res, next) {
 var reqDomain = domain.create();
 reqDomain.on('error', function(err) {
 console.log(err.stack);
 res.statusCode = 500;
 res.end(err.message + '\n');
 reqDomain.dispose();
 });
 reqDomain.add(req);
 reqDomain.add(res);
 reqDomain.run(next);
});

Use forever to start app.js: Forever acts as a daemon process for Node.js that can start, stop, and restart your app.

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forever start app.js

Through these methods, you can improve the stability of Node.js services and prevent the entire service from crashing due to uncaught exceptions.

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[Node.js] Exception Handling in Node.js Express