Write JSON 5

[davestewart]

Background

Right now, we can't write JSON 5 (i.e. comments) back to file.

Apparently even the JSON 5 maintainer doesn't want to touch this.

However, as our use case is so specific we could probably write back to the file using regexp.

Proposal

Something along these lines:

const input = `{
  "example": true,
  "compilerOptions": {
    "target": "esnext",
    "baseUrl": "src",
    "paths": {
      "@/*": ["/*"],
      "@packages/*": ["../packages/*"],
      "@classes/*": ["classes/*"],
      "@app/*": ["app/*"],
      "@data/*": ["app/data/*"],
      "@settings": ["app/settings.js"],
      "@services/*": [
        "app/services/*",
        "../packages/services/*"
      ],
      "@views/*": ["app/views/*"]
    }
  }
}`
    
const rxPaths = /(\s+"paths":\s*)(\{([^}]*)\})/
const rxSpace = /^([ \t]+)"/m

const space = input.match(rxSpace)[1].repeat(3)
const output = input.replace(rxPaths, (match, prefix, block, paths) => {
    console.log(JSON.parse(block))
    return `${prefix}{ ... }`
})

console.log(output)

{
  "example": true,
  "compilerOptions": {
    "target": "esnext",
    "baseUrl": "src",
    "paths": { ... }
  }
}

When writing back to the file, I think we only need to add new aliases at the end, so in theory we don't even need to parse the contents, just append new paths.