Support export { x as default } in namespace declarations

[bluelovers]

Search Terms

Suggestion

options for allow use import { xxx } from 'yyy'; when TS2497 resolves to a non-module entity

without warn or use // @ts-ignore

Error:(11, 19) TS2305: Module has no exported member 'isGitRoot'.
Error:(11, 36) TS2497: Module resolves to a non-module entity and cannot be imported using this construct.

Use Cases

Examples

demo.ts

import gitRoot, { isGitRoot } from 'git-root2';

git-root2

declare function gitRoot(cwd?: string): string;
declare namespace gitRoot {
    function isGitRoot(target: string): boolean;
    function async(cwd?: string): Promise<string>;
}
declare const _default: typeof gitRoot & {
    gitRoot(cwd?: string): string;
    default(cwd?: string): string;
    async(cwd?: string): Promise<string>;
};
export = _default;

Checklist

My suggestion meets these guidelines:
[x] This wouldn't be a breaking change in existing TypeScript / JavaScript code
[x] This wouldn't change the runtime behavior of existing JavaScript code
[ ] This could be implemented without emitting different JS based on the types of the expressions
[ ] This isn't a runtime feature (e.g. new expression-level syntax)

[mhegazy]

So the request is to enable someting like:

function gitRoot(cwd?: string): string {
    return null;
}

namespace gitRoot {
    export function isGitRoot(target: string) {
    }
    export { gitRoot as gitRoot };
    export { gitRoot as default };
    export const __esModule = true;
}

export = gitRoot;

[bluelovers]

my another try

yargs2.ts

import yargs = require('yargs');
import Argv from './core';
export * from './core'; // got overwrite at runtime, but make import didn't have error

Argv(process.argv.slice(2), undefined, {
	supportPassArgs: true,
});

// @ts-ignore
export = Argv;

runtime source of yargs2.js

"use strict";
/**
 * Created by user on 2018/6/1/001.
 */
function __export(m) {
    for (var p in m) if (!exports.hasOwnProperty(p)) exports[p] = m[p];
}
const core_1 = require("./core");
__export(require("./core"));
core_1.default(process.argv.slice(2), undefined, {
    supportPassArgs: true,
});
module.exports = core_1.default;

demo.ts

//import yargs = require('..'); // work
import * as yargs from '..' // work too
import { argv } from 'yargs2' // <=== ts don't know what can import , but without error

console.log(yargs.processArgs);
console.log(yargs.argv); // <=== ts know what `yargs.argv` is

console.log(argv); // <=== ts know what `argv` is

[bluelovers]

looks like this a little near

---

index.ts

import { Trie } from './src/trie'
// @ts-ignore
import { AhoCorasick } from './src/ahocorasick'

// @ts-ignore
export { AhoCorasick, Trie }

// @ts-ignore
export default AhoCorasick

// @ts-ignore
export = AhoCorasick

exports = Object.assign(AhoCorasick, exports);

index.d.ts

import { Trie } from './src/trie';
import { AhoCorasick } from './src/ahocorasick';
export { AhoCorasick, Trie };
export default AhoCorasick;
export = AhoCorasick;

index.js

const trie_1 = require("./src/trie");
// @ts-ignore
const ahocorasick_1 = require("./src/ahocorasick");
// @ts-ignore
exports.default = ahocorasick_1.AhoCorasick;
exports = Object.assign(ahocorasick_1.AhoCorasick, exports);
module.exports = ahocorasick_1.AhoCorasick;

---

temp.ts

import * as AhoCorasick from '..';
import AhoCorasick2 from '..';
import AhoCorasick3 = require('..');

let a1 = new AhoCorasick;
let a2 = new AhoCorasick2;
let a3 = new AhoCorasick3;

let a11 = new AhoCorasick();
let a22 = new AhoCorasick2();
let a33 = new AhoCorasick3();

console.log(a1);
console.log(a2);
console.log(a3);

console.log(a11);
console.log(a22);
console.log(a33);

[bluelovers]

still hope can have this

[bluelovers]

declare function sortObject<T>(object: T, options?: sortObject.IOptions & {
    useSource: true;
}): T;
declare namespace sortObject {
    var default: typeof sortObject;
}

Error:(5, 9) TS1134: Variable declaration expected.

[bluelovers]

1 ~ 3 only can output work to .d.ts

1 will compile nothing in .js , but we can hack it for work
2 will compile bad .js, can't do any hack
3 looks like esm style, so it is bad .js too, can't do any hack

4 is work both of .js and .d.ts, but still hope one of 1~3 is can work, because 4 only work for function

1

1.1

when namespace is declare namespace and namespace name not same as something

export { something as default } is no error

---

1.2

when namespace is namespace

export { something as default } is error

=>

.js

(function (_CallClassWithoutNewDecorator) {
})(_CallClassWithoutNewDecorator || (_CallClassWithoutNewDecorator = {}));

.d.ts

in 1.1 or 1.2 .d.ts will output like this

export { callClassWithoutNewDecorator as default };

2

this is error too, but can output type

export default = callClassWithoutNewDecorator

=>

.d.ts

    const _default: typeof callClassWithoutNewDecorator;
    export default _default;

.js

(function (_CallClassWithoutNewDecorator) {
    export default  = callClassWithoutNewDecorator;
})(_CallClassWithoutNewDecorator || (_CallClassWithoutNewDecorator = {}));

3

export default callClassWithoutNewDecorator still error

=>

.d.ts

export default callClassWithoutNewDecorator;

.js

(function (_CallClassWithoutNewDecorator) {
    export default callClassWithoutNewDecorator;
})(_CallClassWithoutNewDecorator || (_CallClassWithoutNewDecorator = {}));

4

only for callClassWithoutNewDecorator is function

.ts

callClassWithoutNewDecorator.default = callClassWithoutNewDecorator;

=>

.d.ts

declare namespace callClassWithoutNewDecorator {
    var default: typeof callClassWithoutNewDecorator;
}

.js

callClassWithoutNewDecorator.default = callClassWithoutNewDecorator;

[bluelovers]

still need can use default in namespace/module in .ts

because by some reason (performance), for ide

typeof xxx, and function xxx is not same thing

#28018

https://youtrack.jetbrains.com/issue/WEB-35879

https://youtrack.jetbrains.com/issue/WEB-37873