[BUG] `npm outdated --json` only lists a single entry for each package, producing less than without `--json`

[TomStrepsil]

Is there an existing issue for this?

• I have searched the existing issues

This issue exists in the latest npm version

• I am using the latest npm

Current Behavior

npm outdated in a project with workspaces can produce:

Package    Current    Wanted    Latest  Location           Depended by
xxx        1.0.00     1.0.00    1.1.00  node_modules/xxx   workspace1@npm:workspace1name@1.0.0
xxx        1.0.00     1.0.00    1.1.00  node_modules/xxx   workspace2@npm:workspace2name@1.0.0
xxx        1.0.00     1.0.00    1.1.00  node_modules/xxx   rootProject

...but when doing npm outdated --json, only details of the last dependent is shown:

{
  "xxx": {
    "current": "1.0.00",
    "wanted": "1.0.00",
    "latest": "1.1.00",
    "dependent": "rootProject",
    "location": "../rootProject/node_modules/xxx"
  }

Hence, seems like whatever reducer is producing the json is flattening to the last dependent, rather than providing a full list that would be available without --json.

To get around this, one must call npm outdated --json --workspace=xxx for each workspace, then consolidate the results. Presumably the --json option shouldn't produce less information than the tabular format?

Expected Behavior

Either the output needs to include an array per dependency:

{
  "xxx": [
    {
      "current": "1.0.00",
      "wanted": "1.0.00",
      "latest": "1.1.00",
      "dependent": "workspace1",
      "location": "../rootProject/node_modules/xxx"
    },
    {
      "current": "1.0.00",
      "wanted": "1.0.00",
      "latest": "1.1.00",
      "dependent": "workspace2",
      "location": "../rootProject/node_modules/xxx"
    },
    {
      "current": "1.0.00",
      "wanted": "1.0.00",
      "latest": "1.1.00",
      "dependent": "rootProject",
      "location": "../rootProject/node_modules/xxx"
    }
  ]
}

..or if "dependent" isn't needed in the output as a key, just key a map by dependent:

{
  "xxx": {
    "rootProject": {
       "current": "1.0.00",
       "wanted": "1.0.00",
       "latest": "1.1.00",
       "location": "../rootProject/node_modules/xxx"
    },
    "workspace1": {
       "current": "1.0.00",
       "wanted": "1.0.00",
       "latest": "1.1.00",
       "location": "../rootProject/node_modules/xxx"
    },
    "workspace2": {
       "current": "1.0.00",
       "wanted": "1.0.00",
       "latest": "1.1.00",
       "location": "../rootProject/node_modules/xxx"
    }
  }
}

Steps To Reproduce

npm outdated --json with a project that includes workspaces (with or without the --workspaces flag)

Environment

• npm: 9.5.0
• Node.js: v18.16.1
• OS Name: Ventura 13.4.1
• System Model Name: Macbook Pro

[TomStrepsil]

For the final suggestion, could modify makeJSON in /lib/comands/outdated to be:

  makeJSON (list) {
    const out = {}
    list.forEach(dep => {
      const {
        name,
        current,
        wanted,
        latest,
        path,
        type,
        dependent,
        homepage,
      } = dep
      out[dependent] = {
        ...out[dependent],
        [name]: {
          current,
          wanted,
          latest,
          location: path,
        }
      }
      if (this.npm.config.get('long')) {
        out[dependent][name] = {
          ...out[dependent][name],
          type,
          homepage,
        }
      }
    })
    return JSON.stringify(out, null, 2)
  }

...or perhaps using reduce:

  makeJSON (list) {
    const out = list.reduce(
      (
        list,
        {
          name,
          current,
          wanted,
          latest,
          path: location,
          type,
          dependent,
          homepage
        }
      ) => ({
        ...list,
        [dependent]: {
          ...list[dependent],
          [name]: {
            current,
            wanted,
            latest,
            location,
            ...(this.npm.config.get('long')
              ? {
                  type,
                  homepage
                }
              : {})
          }
        }
      }),
      {}
    );
    return JSON.stringify(out, null, 2)
  }