import json does not use object shorthand with es2015 option

[dnalborczyk]

not sure if that is a bug, feature request, or modification request. I'm also not sure if that's the json plugin's responsibility. I'll have to look into it.

Rollup Version

2.58.3

Operating System (or Browser)

n/a

Node Version (if applicable)

n/a

Link To Reproduction

n/a

Expected Behaviour

config.json

{
  "foo": "bar"
}

index.js

import config from "./config.json"

console.log(config);

rollup.config.js

import json from "@rollup/plugin-json";

export default {
  input: "./src/index.js",
  output: {
    file: "./build/bundle.min.js",
    format: "module",
    generatedCode: "es2015", // <---- allow object shorthand (and others)
    name: "bundle",
  },
  plugins: [json()],
};

generates:

var foo = "bar";
const config = {
	foo
};

console.log(config);

I might even expect this, but I'm sure there's a reason:

const config = {
	foo: "bar"
};

console.log(config);

Actual Behaviour

var foo = "bar";
const config = {
	foo: foo // <--- no object shorthand
};

console.log(config);

[kzc]

There's no real advantage, except for slightly more readable non-minified output. Once minified it doesn't matter much.

$ terser actual.js --toplevel --mangle --compress
const o={foo:"bar"};console.log(o);

$ terser actual.js --toplevel --mangle --compress passes=2
console.log({foo:"bar"});

[lukastaegert]

In any case, this would be a feature request for the json plugin to respect the flag. Rollup core does not import json files.

[dnalborczyk]

There's no real advantage, except for slightly more readable non-minified output. Once minified it doesn't matter much.

I agree, although it would be less code. I was under the impression that's (one of the) reasons the generatedCode option was introduced, but I suppose it's only for import/export syntax related things?

In any case, this would be a feature request for the json plugin to respect the flag. Rollup core does not import json files.

was only looking into current json rollup behavior regarding json import assertions/json modules and I'm thinking that it should (eventually/v3) go into core for json import assertions. 🤔

[kzc]

I think it's more of a feature request rather than a bug - the plugin generated code does work correctly.

afaik @rollup/plugin-json outputs the JSON data in pieces so that Rollup can simplify it, but popular minifiers can often simplify the original form:

$ echo 'var o = {a:1, b:2}; console.log(o.a);' | rollup --silent
var o = {a:1, b:2}; console.log(o.a);

$ echo 'var o = {a:1, b:2}; console.log(o.a);' | terser --toplevel -mc
console.log(1);