src-mp

Consume source maps from the command line.

$ npx src-mp functions/index.js.map 6 550
webpack:///node_modules/agentkeepalive/lib/https_agent.js:18:13

  16 |     this.maxCachedSessions = this.options.maxCachedSessions;
  17 |     /* istanbul ignore next */
> 18 |     if (this.maxCachedSessions === undefined) {
     |             ^
  19 |       this.maxCachedSessions = 100;
  20 |     }
  21 |

Objective

The objective of this cli is to easily allow to see what code is behind a line and column of a transpiled code.

With the rise of transpilers (and compilers) for server code, I often found myself debuging stack traces with incomprenhensible combination of lines and column. I would always resort to installing source-map and manually consumming the source map. This tool does just that, but without the need running manually the code.

This package also has a src-mp-extract that will extract all files from the source map.

Help

src-mp <map> <line> <column>

Consume source maps from the command line

Positionals:
  map     Source map file
  line    Line in the transformed file                                  [número]
  column  Column in the transformed file                                [número]

Options:
  --help     Muestra ayuda                                            [booleano]
  --version  Muestra número de versión                                [booleano]

Example

If you are using razzle, typescript and frebase, reading the logs from the command line tools is something like the following:

$ firebase functions:log
2020-03-26T03:08:30.256Z ? myFunction: Unhandled error TypeError: u is not a function
2020-03-26T03:08:30.256Z ? myFunction:     at c.addPersonalization (/srv/functions/index.js:199:115683)
2020-03-26T03:08:30.256Z ? myFunction:     at c.addTo (/srv/functions/index.js:199:115881)
2020-03-26T03:08:30.256Z ? myFunction:     at e.exports.deepMergeDynamicTemplateData (/srv/functions/index.js:121:57684)
2020-03-26T03:08:30.256Z ? myFunction:     at c.applyDynamicTemplateData (/srv/functions/index.js:199:116432)
2020-03-26T03:08:30.256Z ? myFunction:     at c.fromData (/srv/functions/index.js:199:114449)
2020-03-26T03:08:30.256Z ? myFunction:     at new c (/srv/functions/index.js:199:113313)
2020-03-26T03:08:30.256Z ? myFunction:     at Function.create (/srv/functions/index.js:199:119725)
2020-03-26T03:08:30.256Z ? myFunction:     at e.exports.send (/srv/functions/index.js:1:176323)
2020-03-26T03:08:30.256Z ? myFunction:     at /srv/functions/index.js:204:548418
2020-03-26T03:08:30.256Z ? myFunction:     at Generator.next (<anonymous>)
2020-03-26T03:08:30.256Z ? myFunction:     at o (/srv/functions/index.js:204:547402)

This tool helps you to understand where the error really was:

$ npx src-mp functions/index.js.map 199 115683
webpack:///node_modules/@sendgrid/helpers/classes/mail.js:262:11

  260 |     //If this is dynamic, set dynamicTemplateData, or set substitutions
  261 |     if (this.isDynamic) {
> 262 |       this.applyDynamicTemplateData(personalization);
      |           ^
  263 |     }
  264 |     else {
  265 |       this.applySubstitutions(personalization);

Extract

src-mp-extract <map> <output>

Extract all files from source map

Positionals:
  map     Source map file
  output  Output folder

Options:
  --help        Muestra ayuda                                         [booleano]
  --version     Muestra número de versión                             [booleano]
  --filter, -f  Regexp in order to filter out files    [defecto: "node_modules"]