TypeScript error with extendMoment()

[nareshbhatia]

Following the ES6 installation instructions to use moment-range with TypeScript 3.4.5 I was getting the following error on extendMoment():

Argument of type 'typeof import("/Users/narbhati/projects/slidesup/node_modules/moment/moment.d.ts")' is not assignable to parameter of type 'typeof import("/Users/narbhati/projects/slidesup/node_modules/moment/moment.d.ts")'.
Property 'default' is missing in type 'typeof import("/Users/narbhati/projects/slidesup/node_modules/moment/moment.d.ts")' but required in type 'typeof import("/Users/narbhati/projects/slidesup/node_modules/moment/moment.d.ts")'. TS2345

I had to change the moment import statement as follows to get rid of this error:

// import Moment from 'moment';
import * as Moment from 'moment';
import { extendMoment } from 'moment-range';

const moment = extendMoment(Moment);

Surprisingly, the original import statement works perfectly fine in other files that do not use moment-range (I use esModuleInterop: true in tsconfig).

For example, this works fine:

import moment from 'moment';
import 'moment-timezone';
import 'moment-duration-format';

Would be good to document the correct way to use moment-range with TypeScript.

[ddehghan]

They only way I got this to work in "typescript": "3.4.5"

const Moment = require('moment');
import {extendMoment} from 'moment-range';

const moment = extendMoment(Moment);

[TristanJM]

Thanks @nareshbhatia! I've updated the docs to reflect that fix :)
Does this also work for your case @ddehghan?

[nareshbhatia]

@TristanJM, it's a workaround at best :-). TypeScript is getting very popular in the React circles now, so finding a natural solution would be good.

[ddehghan]

Sadly above also failed and gave me lint errors. I fixed it like this.

import * as moment from 'moment';
import {extendMoment} from 'moment-range';

const {range} = extendMoment(moment);

const r = range(moment.utc('2019-10-01T00:00:00.000Z'), now);

but even this latest iteration has a problem where calling moment default functions causes this error.

const xxx = moment('2019-10-01T00:00:00.000Z');

This expression is not callable.
  Type 'typeof import(".../node_modules/moment/moment.d.ts")' has no call signatures.ts(2349)
subscription.ts(15, 1): Type originates at this import. A namespace-style import cannot be called or constructed, and will cause a failure at runtime. Consider using a default import or import require here instead.

[minamorl]

This workaround works for me:

// This line has changed. I think "* as Moment" is wrong.
import Moment from "moment"; 

import { extendMoment } from "moment-range";

// Current latest release has wrong type definition,
// so I put any casting to avoid errors.
const moment = extendMoment(Moment as any);

[Mach12]

I've come across this problem and came up with the following:

import * as Moment from 'moment'
import { extendMoment } from 'moment-range'

const { default: moment, range: momentRange } = extendMoment(Moment)

I couldn't find an approach that allows to write moment.range without going through any, but this seems to work in TS 4.4 and neither TS nor our linter complains.