6.0.0-beta.x regression, array of data imported as JSON file get transformed to an object, why?

[ghiscoding]

Describe the bug

I have a JSON file with the following structure

[
  {"name":"Ethel Price","gender":"female","company":"Enersol","id":1,"category":{"id":1,"name":"Gold"}},
  {"name":"Claudine Neal","gender":"female","company":"Sealoud","id":2,"category":{"id":1,"name":"Gold"}},
]

when I import the file via an import, it is returning an array (good) of data in Vite 5.x but in 6.x it imports the same file as an object (bad) for unknown reason when I expect it to remain an array. This seems like a regression when comparing to Vite 5.x

Reproduction

https://stackblitz.com/edit/vitejs-vite-qwnzvw?file=main.js

Steps to reproduce

Just run the Stackblitz provided.

running the same Stackblitz with Vite 5.x I get this

but running with Vite 6.0-beta, I get this (notice the prototype changes to Object instead of Array)

System Info

System:
    OS: Windows 10 10.0.19045
    CPU: (12) x64 Intel(R) Core(TM) i7-8750H CPU @ 2.20GHz
    Memory: 1.71 GB / 15.85 GB
  Binaries:
    Node: 20.13.1 - C:\Program Files\nodejs\node.EXE
    Yarn: 1.22.22 - ~\AppData\Roaming\npm\yarn.CMD
    npm: 10.9.0 - C:\Program Files\nodejs\npm.CMD
    pnpm: 9.12.2 - C:\OwnCloudDev10\GitHub\slickgrid-universal\node_modules\.bin\pnpm.CMD
  Browsers:
    Edge: Chromium (127.0.2651.74)
    Internet Explorer: 11.0.19041.4355

Used Package Manager

pnpm

Logs

No response

Validations

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[sapphi-red]

It seems I broke it in #18303. For now, setting json.stringify: false would work.

[ghiscoding]

Ah thanks for the info, I'm assuming that it's because of line 54 since pretty everything in JS is derived from object and that includes arrays. Perhaps the if condition should skip arrays?

vite/packages/vite/src/node/plugins/json.ts

Lines 51 to 55 in f65d6ae

	if (options.stringify !== false) {
	if (options.namedExports) {
	const parsed = JSON.parse(json)
	if (typeof parsed === 'object' && parsed != null) {
	const keys = Object.keys(parsed)

Taking a look at the isObject npm package, with 48M download, they also check for array to know if it's an object or not

https://github.com/jonschlinkert/isobject/blob/master/index.js

export default function isObject(val) {
  return val != null && typeof val === 'object' && Array.isArray(val) === false;
};

[bluwy]

We also have a isObject utility that we can use:

vite/packages/vite/src/node/utils.ts

Lines 387 to 389 in 8a7af50

	export function isObject(value: unknown): value is Record<string, any> {
	return Object.prototype.toString.call(value) === '[object Object]'
	}