moment-duration-format.d.ts Definition Not Extending Moment Module

Question

Any idea why this doesn’t work or how I can extend the duration interface to support the format function?

declare module 'moment' {
     interface Duration {
       format(template: string, precision?: string, settings?: any): string;
     }

}

when used as:

moment.duration(minutes, 'minutes').format('mm');

I’m getting the error that ‘format' does not exist on type ‘Duration'

Bruin

Answer 1

First, install types:

npm install --save-dev @types/moment-duration-format

Second, import them in your file:

/// <reference path='../..your-path.../node_modules/@types/moment-duration-format/index.d.ts' />
import * as moment from 'moment';
import 'moment-duration-format';

Then you can use

moment.duration(minutes, 'minutes').format('mm');

Healy

npm install --save-dev @types/moment-duration-format solved my problem, while npm install moment-duration-format didn't. – Pappose

Answer 2

Imports:

import * as moment from 'moment';
import 'moment-duration-format';

Outside of your class, define the interfaces:

interface Duration extends moment.Duration {
  format: (template?: string, precision?: number, settings?: DurationSettings) => string;
}

interface DurationSettings {
  forceLength: boolean;
  precision: number;
  template: string;
  trim: boolean | 'left' | 'right';
}

Then in your code:

const duration = moment.duration(minutes, 'minutes') as Duration;
return duration.format('mm');

If you defined your Duration interface in another file, you will need to export and import it as well.

Shinar

I'm still getting errors in my code. Property 'duration' does not exist on type 'typeof 'moment''. – Bruin

I'd need to have a look at your code to better understand where your error comes from. But do have a look at my answer, I updated the interface definitions. I don't think it will solve your problem, but once fixed, it will provide better autocomplete. – Shinar

Works like a charm! Thanks – Pung

Answer 3

You need to have the following dependencies installed:

"dependencies": {
  "@types/moment-duration-format": "2.2.2",
  "moment": "2.24.0",
  "moment-duration-format": "2.3.2"
}

If that's the case then you need these imports in the exact same order:

import * as moment from 'moment';
import 'moment-duration-format';

Afterwards you should be able to do this:

const seconds: number = Math.floor(process.uptime());
const formatted: string = moment.duration(seconds, 'seconds').format({
  precision: 0,
  template: 'y [years], w [weeks], d [days], h [hours], m [minutes], s [seconds]',
});

Liman

Answer 4

you should use namespace instead of module

declare namespace moment {
     interface Duration {
       format(template: string, precision?: string, settings?: DurationSettings): string;
     }

}

and settings for "moment-duration-format": "^2.3.2"

        interface DurationSettings {
                trim: boolean | 'left' | 'right';
                useGrouping: boolean;
                usePlural: boolean;
                useLeftUnits: boolean;
                precision: number;
                useSignificantDigits: boolean;
                trunc: boolean;
                forceLength: boolean;
                minValue: number;
                maxValue: number;
                largest: number;
        }

Trapeze