Use consistent coding styling between projects

I have noticed that the CLI starter, the documentation, the main project, and officials modules have all different set of TSLint rules applied to them. I propose that we normalize all those rules by enforcing one set of well documented and thought rules, such as the http://airbnb.io/javascript, across all the different official projects.

That would make the reading easier, add constancy to the different projects, and enforce many good practices that have long been discussed.

Prettier could still be used and would work with the linting rules by using the following ESLint extensions:

'airbnb-base',
'plugin:import/typescript',
'plugin:@typescript-eslint/recommended',
'prettier',
'prettier/@typescript-eslint',

If that makes, I would open the different PRs on the projects to apply the configuration change.

[hboylan]

My current setup in Nest project: https://gist.github.com/hboylan/3e707e1bb12b09388540779a25d217ae

.eslintrc

{
  "extends": ["prettier"],
  "plugins": ["prettier"],
  "parser": "@typescript-eslint/parser",
  "parserOptions": {
    "ecmaVersion": 6,
    "sourceType": "module"
  },
  "rules": {
    "prettier/prettier": "error"
  }
}

.prettierrc

{
  "semi": false,
  "singleQuote": true,
  "tabWidth": 2,
  "trailingComma": "all"
}

package.json

{
  "scripts": {
    "lint": "eslint src/**/*.ts"
  },
  "dependencies": {
    "@typescript-eslint/eslint-plugin": "^2.3.2",
    "@typescript-eslint/parser": "^2.3.2",
    "eslint": "^6.5.1",
    "eslint-config-prettier": "^6.3.0",
    "eslint-plugin-prettier": "^3.1.1",
    "prettier": "^1.18.2"
  }
}

For VS Code:

.vscode/settings.json

{
  "editor.codeActionsOnSave": {
    "source.fixAll.eslint": true
  }
}

[IGassmann]

Sure! I will open a PR first in https://github.com/nestjs/typescript-starter to start simple.