sourcemap-decorate-callsites

Decorate callsites with methods that return the sourcemapped file/line/column locations.
Supports both file references and inline source maps.

Installation

$ npm install --save sourcemap-decorate-callsites

Usage

var errorCallsites = require('error-callsites')
var decorateCallsites = require('sourcemap-decorate-callsites')
var someModule = require('some-module')

someModule.doAsyncThing(function (err) {
  if (!err) {
    return console.log('yaywin')
  }

  decorateCallsites(errorCallsites(err), function (sourcemapErr, callsites) {
    printCallsites(err, callsites)
  })
})

function printCallsites(err, callsites) {
  console.log('Error: %s', err.message)
  callsites.forEach(function (callsite) {
    console.log(
      '  in %s:%s:%s',
      callsite.getFileName(),
      callsite.getLineNumber(),
      callsite.getColumnNumber()
    )
  })
}

How it works

• Passed callsites are resolved to filenames
• Filenames referenced are read from filesystem
• Source files are traversed, looking for references to a source map (//# sourceMappingURL=some.js.map)
• The source map is read from filesystem (or parsed from base64 in the case of inline source maps)
• A source map consumer is created using the source-map module and cached in-memory
• The following functions for each callsite are modified to return the information from the source map if available:
  • getFileName()
  • getLineNumber()
  • getColumnNumber()
• When called, these functions will resolve the generated location to the original location based on the source map

Notes

• To debug why a sourcemap can't be resolved or results in an error, you may pass DEBUG=sourcemap-decorate-callsites to your Node application, which will print debug info while resolving.

License

MIT-licensed. See LICENSE.