How to specify a "caused by" in a JavaScript Error?
What I finally did is:
try { this.config = JSON.parse(fs.readFileSync(path));} catch(err) { var newErr = new Error('Problem while reading the JSON file'); newErr.stack += '\nCaused by: '+err.stack; throw newErr;}
Joyent released a Node.js package that can be used exactly for that. It is called VError. I paste an example of how you would use the pacakge:
var fs = require('fs');var filename = '/nonexistent';fs.stat(filename, function (err1) { var err2 = new VError(err1, 'stat "%s"', filename); console.error(err2.message);});would print the following:
stat "/nonexistent": ENOENT, stat '/nonexistent'
There is a new Error Cause proposal for ECMAScript. It progressed very fast, is already at stage 3 and looks likely to be adopted.
https://github.com/tc39/proposal-error-cause
You would provide the cause as an error option:
throw new Error(`Couldn't parse file at path ${filePath}`, { cause: err });The ES proposal only formalize it on the language level, but browsers/NodeJS will normally log the full causal chain in practice (see https://github.com/nodejs/node/issues/38725)