How do I change the language of moment.js?

I had to import also the language:

import moment from 'moment'
import 'moment/locale/es'  // without this line it didn't work
moment.locale('es')

Then use moment like you normally would

console.log(moment(date).fromNow())

You need moment.lang (WARNING: lang() is deprecated since moment 2.8.0, use locale() instead):

moment.lang("de").format('LLL');

http://momentjs.com/docs/#/i18n/

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As of v2.8.1, moment.locale('de') sets the localization, but does not return a moment. Some examples:

var march = moment('2017-03')
console.log(march.format('MMMM')) // 'March'

moment.locale('de') // returns the new locale, in this case 'de'
console.log(march.format('MMMM')) // 'March' still, since the instance was before the locale was set

var deMarch = moment('2017-03')
console.log(deMarch.format('MMMM')) // 'März'

// You can, however, change just the locale of a specific moment
march.locale('es')
console.log(march.format('MMMM')) // 'Marzo'

In summation, calling locale on the global moment sets the locale for all future moment instances, but does not return an instance of moment. Calling locale on an instance, sets it for that instance AND returns that instance.

Also, as Shiv said in the comments, make sure you use "moment-with-locales.min.js" and not "moment.min.js", otherwise it won't work.