Convert from Instagram Shortcode to Id and Back using big-integer

InstagramIdConvert.js

var bigint = require( 'big-integer' )

var lower = 'abcdefghijklmnopqrstuvwxyz';
var upper = lower.toUpperCase();
var numbers = '0123456789'
var ig_alphabet =  upper + lower + numbers + '-_'
var bigint_alphabet = numbers + lower

function toShortcode( longid )
{
	var o = bigint( longid ).toString( 64 )
	return o.replace(/<(\d+)>|(\w)/g, (m,m1,m2) =>
	{
		return ig_alphabet.charAt( ( m1 )
		  ? parseInt( m1 ) 
		  : bigint_alphabet.indexOf( m2 ) )
	});
}

function fromShortcode( shortcode )
{
	var o = shortcode.replace( /\S/g, m =>
	{
		var c = ig_alphabet.indexOf( m )
		var b = bigint_alphabet.charAt( c ) 
		return ( b != "" ) ? b : `<${c}>`
	} )	
	return bigint( o, 64 ).toString( 10 )
}

toShortcode(  '908540701891980503' ) // s.b. 'ybyPRoQWzX'
fromShortcode( 'ybyPRoQWzX' ) // s.b. '908540701891980503'

Same problem as pierrocknroll ^

Same here. Spent 2 days trying to fix this basic conversion which FB could do it for us. It makes total sense.

For anyone comes across this... this short code converter only works to generate the ig_id, but the facebook graph api ids are different and this doesn't work for thate

Examples shown above:
17889455560051444
17883949432067035

These are both ids from the ig graph api