How convert steamID64 to steamID3

[mrxbell]

I need convert steamID64 to steamID3 . If i use 

var steamid3 = steamid64 & 0xffffffff;

not true when using 64 bit system. Thanks ! 

Edited January 25, 2017 by mrxbell

[Dr. McKay]

https://www.npmjs.com/package/steamid

var SteamID = require('steamid');
var steamid3 = (new SteamID(steamid64)).steam3();

If you want the accountID and not the Steam3 rendered format as your title implies ([u:1:46143802]) then you just want to do:

var SteamID = require('steamid');
var accountID = (new SteamID(steamid64)).accountid;