Completion list for JSON files imported using CommonJS require

[vojtechhabarta]

Fixes #7071

This change provides completion lists for JSON files that are loaded using CommonJS require function.
For example for json1.json file

{
    "foo": "foo",
    "bar": "bar"
}

and test.ts file

var json1 = require("./json1");
json1. // <---

TypeScript compiler now provides completion list with foo and bar items.

Implementation

It is implemented as proposed in #7071 (comment) comment.

• JSON files are parsed using TypeScript parser parseObjectLiteralExpression() function
• node module resolver is extended to support .json extension
• added ScriptKind.JSON

EDIT: removed description of my problem with tests (solved by updating dependencies using npm install)

[msftclas]

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[mhegazy]

//cc @DanielRosenwasser who was looking into this earlier.

[piotrwitek]

+1

[mhegazy]

@vojtechhabarta sorry for the delay. I am a bit busy with TS 2.0 release at the moment, but i would love to get this change in once that is out.

[aluanhaddad]

It would be nice if this could be generalized. If the user writes an import statement like

import * as json1 from './json1';

or

import json1 from './json1'; // iff "allowSyntheticDefaultImports": true

it should work just as well. @mhegazy what do you think?

[vojtechhabarta]

I wanted to resubmit this PR based on current master but I don't know how to solve one thing.

Recently #11370 was merged which adds following change: "Return type of require call is from external module resolution only if it doesn't resolve to local module" (checker.ts:12797 - https://github.com/Microsoft/TypeScript/pull/11370/files).
However this resolution is also used when there is node.d.ts in compilation so in this example test:

// @allowjs: true
// @outDir: dist
// @Filename: m1.js
export var a = 42;

// @Filename: m2.js
const m1 = require("./m1");
const a = m1.a;

// @Filename: node.d.ts
interface NodeRequireFunction {
    (id: string): any;
}
interface NodeRequire extends NodeRequireFunction {
}
declare var require: NodeRequire;

type of m1.a in any instead of number as it was before #11370.

Same applies for require with JSON file. I don't know how to distinguish between require from node.d.ts and other require cases.

@mhegazy, @sheetalkamat do you have any idea how this could be improved so it works also with node.d.ts?

[sheetalkamat]

Checkout this #11819

[vojtechhabarta]

Thanks @sheetalkamat for the link, that's exactly what I needed.

@mhegazy I rebased this PR on current master branch.

[mhegazy]

closing in favor of #13665