TypeScript

Day.js ships with official type declarations for TypeScript in NPM package out of the box.

Install via NPM

npm install dayjs

Import and use in your TypeScript file

import * as dayjs from 'dayjs';
dayjs().format();

Have trouble importing Day.js?

If your tsconfig.json contains the following config, you must do the default import workflow import dayjs from 'dayjs':

{
  //tsconfig.json
  "compilerOptions": {
    "esModuleInterop": true,
    "allowSyntheticDefaultImports": true
  }
}

If you don't have these config above, the default import won't work, and you'll continue to have to use import * as dayjs from 'dayjs'

Locale and plugin import

To use locale and plugin, you first need to import the targeting language and plugin.

import * as dayjs from 'dayjs';
import * as isLeapYear from 'dayjs/plugin/isLeapYear'; // import plugin
import 'dayjs/locale/zh-cn'; // import locale

dayjs.extend(isLeapYear); // use plugin
dayjs.locale('zh-cn'); // use locale