This question in about the frontend side (Website)

var foo = openerp._t('bar')

gives:

#. module: my_module
#. openerp-web
#: code:addons/my_module/static/src/js/main.js:351
#, python-format
msgid "bar"
msgstr ""

in the generated .pot file.

However, the translation does not work.

If I put 'bar' in the, let's say, french translation file (fr.po), restart and update my module, the translation appears in the database. I can see it at Settings/Translation/Translated terms, but not on my custom view, where I insert the javascript string.

But I know that the function works sometimes. Here's a sample from a javascript console:

openerp._t('foo')
> "foo"
openerp._t('Title')
> "Civilité"

Update:

This works in console, but not in code:

var translationDataBase = new openerp.TranslationDataBase(),
    session = new openerp.Session(),
    lang = openerp.website.get_context().lang;
    
translationDataBase.load_translations(session, ['my_module'], lang);
var _t = translationDataBase.build_translation_function();

Update 2:

It seems that it has to do with Deferred objects :/ Because I set a timeout before calling _t('foo'), and that worked!