Qué? Por qué

Para bien o para mal, el contenido dentro de package.json ha ido creciendo con una complejidad cada vez mayor. En los primeros días de npm, el archivo era simplemente algunos metadatos de las dependencias de las que dependía un proyecto / paquete. Los proyectos crecieron en complejidad y ahora las pruebas, los marcos y otras bibliotecas son todas dependencias que parecen estar juntas. Hubo cierta separación entre dependencies y devDependencies , pero esa es una categorización aproximada. Ahora tenemos herramientas que contribuyen y residen dentro del package.json con mayor complejidad ... configuraciones de monorepo, configuraciones de lint, configuraciones de commit, git hooks, nodemon, jest, la lista continúa ...

Los comentarios ofrecen una forma de explicar toda la complejidad.

Sigo pensando que los mantenedores de bibliotecas deberían seguir usando JSON puro para la compatibilidad con versiones anteriores, pero al menos ofrecer este avance permitirá a los creadores de proyectos (la gran mayoría de los usuarios) la capacidad de documentar su package.json. Por supuesto, json permite que las claves duplicadas sirvan como comentarios, pero esto se parece demasiado a un truco.

Cómo

Comportamiento actual

Un ejemplo redactado y elaborado:

{
  "name": "my-project",
  "version": "0.0.1",
  "license": "MIT",
  "scripts": {
    "build": "a bunch of scripts",
    "ci": "a bunch of scripts",
    "ci:local": "a bunch of scripts",
    "docsite": "a bunch of scripts",
    "docsite:combiner": "a bunch of scripts",
    "docsite:sassdoc": "a bunch of scripts",
    "docsite:tsdoc": "a bunch of scripts",
    "e2e": "a bunch of scripts",
    "html-sketchapp-install": "a bunch of scripts",
    "html-sketchapp": "a bunch of scripts",
    "lint": "a bunch of scripts",
    "sassdoc": "a bunch of scripts",
    "sassdoc:comp": "a bunch of scripts",
    "sassdoc:core": "a bunch of scripts",
    "start": "a bunch of scripts",
    "start:hmr": "a bunch of scripts",
    "start:qa": "a bunch of scripts",
    "start:dev": "a bunch of scripts",
    "generate-examples": "a bunch of scripts",
    "rebuild-markdown": "a bunch of scripts",
    "watch-examples": "a bunch of scripts",
    "test:cov": "a bunch of scripts",

    "test": "jest",
    "test:watch": "jest --watch",
    "test:cc": "jest --coverage"
  },
  "config": {
    "commitizen": {
      "path": "./node_modules/cz-conventional-changelog"
    }
  },
  "dependencies": {
    "@angular-devkit/build-angular": "~0.900.1",
    "@angular-devkit/build-ng-packagr": "~0.900.1",
    "@angular-devkit/core": "~9.0.0",
    "@angular-devkit/schematics": "~9.0.0",
    "@angular/animations": "~9.0.0",
    "@angular/cdk": "~9.0.0",
    "@angular/cli": "~9.0.1",
    "@angular/common": "~9.0.0",
    "@angular/compiler": "~9.0.0",
    "@angular/compiler-cli": "~9.0.0",
    "@angular/core": "~9.0.0",
    "@angular/forms": "~9.0.0",
    "@angular/language-service": "~9.0.0",
    "@angular/platform-browser": "~9.0.0",
    "@angular/platform-browser-dynamic": "~9.0.0",
    "@angular/router": "~9.0.0",
    "@angular/service-worker": "~9.0.0",
    "@angularclass/hmr": "2.1.3",
    "@ngrx/effects": "~8.6.0",
    "@ngrx/entity": "~8.6.0",
    "@ngrx/router-store": "~8.6.0",
    "@ngrx/schematics": "~8.6.0",
    "@ngrx/store": "~8.6.0",
    "@ngrx/store-devtools": "~8.6.0",
    "@types/jasmine": "~3.5.0",
    "@types/jasminewd2": "~2.0.3",
    "@types/lodash-es": "^4.17.3",
    "@types/node": "^12.11.1",
    "classlist.js": "1.1.20150312",
    "codelyzer": "^5.1.2",
    "console-polyfill": "0.3.0",
    "core-js": "^2.5.4",
    "cz-conventional-changelog": "1.2.0",
    "date-fns": "1.30.1",
    "highcharts": "^7.2.1",
    "highcharts-angular": "^2.4.0",
    "html2canvas": "^1.0.0-rc.5",
    "jasmine-core": "~3.5.0",
    "jasmine-spec-reporter": "~4.2.1",
    "karma": "~4.3.0",
    "karma-chrome-launcher": "~3.1.0",
    "karma-coverage-istanbul-reporter": "~2.1.0",
    "karma-jasmine": "~2.0.1",
    "karma-jasmine-html-reporter": "^1.4.2",
    "lodash-es": "^4.17.11",
    "mime": "~2.4.2",
    "ngrx-store-freeze": "0.2.4",
    "ngx-monaco-editor": "~8.0.0",
    "ngx-quill": "^7.3.12",
    "pdfmake": "^0.1.64",
    "prettier": "1.19.1",
    "protractor": "~5.4.3",
    "quill": "^1.3.7",
    "rxjs": "~6.5.4",
    "rxjs-compat": "^6.0.0",
    "standard-changelog": "1.0.19",
    "svgxuse": "1.2.6",
    "ts-node": "~8.3.0",
    "tsickle": "^0.35.0",
    "tslib": "^1.10.0",
    "tslint": "~5.18.0",
    "typescript": "~3.7.5",
    "web-animations-js": "~2.3.1",
    "zone.js": "~0.10.2"
  },
  "devDependencies": {
    "@types/jest": "^24.0.6",
    "jest": "^24.1.0",
    "jest-preset-angular": "^6.0.2",
    "ts-node": "~7.0.1",
    "typescript": "3.2.4"
  },
  "jest": {
    "preset": "jest-preset-angular",
    "setupTestFrameworkScriptFile": "<rootDir>/setupJest.ts"
  },
  "nodemonConfig": {
    "ignore": [
      "**/example-module.ts"
    ],
    "watch": [
      "./a/bunch/of/stuff"
    ],
    "ext": "js ts md html"
  },
  "workspaces": {
    "packages": [
      "packages/*"
    ],
    "nohoist": [
      "**"
    ]
  }
}

Comportamiento esperado

Un ejemplo de package.json con comentarios.

{
  "name": "my-project",
  "version": "0.0.1",
  "license": "MIT",
  "scripts": {
    "build": "a bunch of scripts",
    "ci": "a bunch of scripts",
    "ci:local": "a bunch of scripts",
    // for building our documentation site
    "docsite": "a bunch of scripts",
    "docsite:combiner": "a bunch of scripts",
    "docsite:sassdoc": "a bunch of scripts",
    "docsite:tsdoc": "a bunch of scripts",
    "e2e": "a bunch of scripts",
    "lint": "a bunch of scripts",
    "sassdoc": "a bunch of scripts",
    "sassdoc:comp": "a bunch of scripts",
    "sassdoc:core": "a bunch of scripts",
    "start": "a bunch of scripts",
    "start:hmr": "a bunch of scripts",
    "start:qa": "a bunch of scripts",
    "start:dev": "a bunch of scripts",
    "generate-examples": "a bunch of scripts",
    "rebuild-markdown": "a bunch of scripts",
    "watch-examples": "a bunch of scripts",
    "test:cov": "a bunch of scripts",

    "test": "jest",
    "test:watch": "jest --watch",
    "test:cc": "jest --coverage"
  },
  "config": {
    "commitizen": {
      "path": "./node_modules/cz-conventional-changelog"
    }
  },
  "dependencies": {
    // ANGULAR
    "@angular-devkit/build-angular": "~0.900.1",
    "@angular-devkit/build-ng-packagr": "~0.900.1",
    "@angular-devkit/core": "~9.0.0",
    "@angular-devkit/schematics": "~9.0.0",
    "@angular/animations": "~9.0.0",
    "@angular/cdk": "~9.0.0",
    "@angular/cli": "~9.0.1",
    "@angular/common": "~9.0.0",
    "@angular/compiler": "~9.0.0",
    "@angular/compiler-cli": "~9.0.0",
    "@angular/core": "~9.0.0",
    "@angular/forms": "~9.0.0",
    "@angular/language-service": "~9.0.0",
    "@angular/platform-browser": "~9.0.0",
    "@angular/platform-browser-dynamic": "~9.0.0",
    "@angular/router": "~9.0.0",
    "@angular/service-worker": "~9.0.0",
    "@angularclass/hmr": "2.1.3",

    "zone.js": "~0.10.2",
    "rxjs": "~6.5.4",
    "rxjs-compat": "^6.0.0",


    // polyfills for angular 
    "console-polyfill": "0.3.0",
    "core-js": "^2.5.4",
    "classlist.js": "1.1.20150312",
    "svgxuse": "1.2.6",
    "web-animations-js": "~2.3.1",

    // lint management

    "codelyzer": "^5.1.2",
    "prettier": "1.19.1",
    "tslint": "~5.18.0",

    // changelog creation
    "cz-conventional-changelog": "1.2.0",
    "standard-changelog": "1.0.19",

    // ngrx state management 
    "@ngrx/effects": "~8.6.0",
    "@ngrx/entity": "~8.6.0",
    "@ngrx/router-store": "~8.6.0",
    "@ngrx/schematics": "~8.6.0",
    "@ngrx/store": "~8.6.0",
    "@ngrx/store-devtools": "~8.6.0",
    "ngrx-store-freeze": "0.2.4",


    // library deps

    // Graphs support
    "highcharts": "^7.2.1",
    "highcharts-angular": "^2.4.0",

    // for creating pdfs
    "html2canvas": "^1.0.0-rc.5",
    "pdfmake": "^0.1.64",

    // rich text support
    "ngx-quill": "^7.3.12",
    "quill": "^1.3.7",




    // testing
    "jasmine-core": "~3.5.0",
    "jasmine-spec-reporter": "~4.2.1",
    "karma": "~4.3.0",
    "karma-chrome-launcher": "~3.1.0",
    "karma-coverage-istanbul-reporter": "~2.1.0",
    "karma-jasmine": "~2.0.1",
    "karma-jasmine-html-reporter": "^1.4.2",

    // e2e testing
    "protractor": "~5.4.3",

    // typscript and compilation
    "ts-node": "~8.3.0",
    "tsickle": "^0.35.0",
    "tslib": "^1.10.0",
    "typescript": "~3.7.5",

    // misc deps
    "date-fns": "1.30.1",
    "lodash-es": "^4.17.11",
    "mime": "~2.4.2"
  },
  "devDependencies": {
    "@types/jasmine": "~3.5.0",
    "@types/jasminewd2": "~2.0.3",
    "@types/lodash-es": "^4.17.3",
    "@types/node": "^12.11.1",
    "@types/jest": "^24.0.6",
    "jest": "^24.1.0",
    "jest-preset-angular": "^6.0.2",
    "ts-node": "~7.0.1",
    "typescript": "3.2.4"
  },
  // complicated jest configuration here
  "jest": {
    "preset": "jest-preset-angular",
    "setupTestFrameworkScriptFile": "<rootDir>/setupJest.ts"
  },
  // use nodemon to trigger stuff
  "nodemonConfig": {
    "ignore": [
      "**/example-module.ts"
    ],
    "watch": [
      "./a/bunch/of/stuff"
    ],
    "ext": "js ts md html"
  },
  // extra libraries we are creating internally
  "workspaces": {
    "packages": [
      "packages/*"
    ],
    "nohoist": [
      "**"
    ]
  }
}

Referencias

https://github.com/microsoft/node-jsonc-parser

TypeScript usa comentarios en sus archivos tsconfig.json.