Explicit error messages with VError

Today I will present you one of my favorite NPM modules. VError makes your errors more explicit.

I will not expose all the features here and just explain why I think this module is very useful. So don't hesitate to read the official documentation here

The thing I like with VError is the feature of building a composite error message through all applicative layers the error goes through.

Let see an example :

const VError = require('verror') function model(json) { return JSON.parse(json) } function controller(json) { try { model(json) } catch (err) { const error = new VError(err, 'Model fail to parse json') throw error } } function routeHandler(rawJSON) { try { const data = controller(rawJSON) return data } catch (err) { const error = new VError(err, 'Controller fail to use json') throw error } } routeHandler('invalid json') 

This script will generate the following error message :
VError: Controller fail to use json: Model fail to parse json: Unexpected token i in JSON at position 0

This is much more explicit to see than : SyntaxError: Unexpected token i in JSON at position 0

Also you can add some contextual information for each VError layers and get them at the end with the VError.info() function see documentation here

Examples :

const error = new VError({ name: 'SERVICE_UNAVAILABLE', info: { json: rawJSON }, cause: err, }, 'Controller fail to use json') console.log(VError.info(error)) // { json: 'invalid json' } console.log(error.name) // SERVICE_UNAVAILABLE 

Let me know in the comments if you use it already or if you will in the future and what are your feedbacks about VError.