__() in javascript

gistfile1.js

window._lang = 'fr';

var translations = {
  'String to Translate': 'Chaîne à traduire',
  'something': 'quelque chose'
};    
    
var __ = function(msgid) {
  if (window._lang === 'fr' && (msgid in translations)) {
    return translations[msgid];
  } else {
    return msgid;
  }
};