moment.updateLocale('en', {
      weekdaysMin : String[]
});
moment.updateLocale('en', {
      weekdaysMin : Function
});

npm install moment

// Importing moment module 
const moment = require('moment'); 
let localeData = moment.updateLocale('en', 
    { 
        weekdaysMin: ["Su", "Mo", "Tu", "We", "Th", "Fr", "Sa"] 
    }); 
let a = localeData.weekdaysMin(); 
console.log("The array of all Minimal Weekday Abbreviations stored", a);

The array of all minimal weekday abbreviations stored
[
  'Su', 'Mo',
  'Tu', 'We',
  'Th', 'Fr',
  'Sa'
]

// Importing moment module 
const moment = require('moment'); 
let localeData = moment.updateLocale('en', { 
    weekdaysMinarr: [ 
        "Su_gfg", "Mo_gfg", "Tu_gfg", "We_gfg", "Th_gfg", "Fr_gfg", "Sa_gfg"], 
    weekdaysMin: function (momentToFormat, format) { 
        return this._weekdaysMinarr[momentToFormat.day()]; 
    } 
}); 
let a = localeData.weekdaysMin(moment()); 
console.log("The current Weekday of Minimal Weekday Abbreviations is:", a);

The current Weekday of Minimal Weekday Abbreviations is: We_gfg