How to change locale through the language picker

This is my configuration but locale doesn’t change, if I change defalutLocale in initial configuration webpage is translated. But if I pick different language from the dropdown nothing changes

i18n.configure({
  locales: ['eng', 'rus'],
  defaultLocale: 'rus',
  directory: __dirname + '/static/locales',
  cookiename: 'locale'
});

app.use(function (req, res, next) {
    res.locals.__ = res.__ = function() {
        return i18n.__.apply(req, arguments);
    };
    next();
});

app.get('/:locale', function (req, res) {
    res.cookie('locale', req.params.locale);
    i18n.setLocale(i18n, req.params.locale);
    res.redirect(req.headers.referer);
});

[mashpie]

haha I didn’t spot that either… cookie vs. cookiename - the later is more explicit => thinking of an alias…

[mashpie]

hbs helpers are always tricky to implement as they maintain their own scope[s] in nested levels. I recently setup some helpers by use of this.__() in helper methods. Beware that this will only work on @root level in hbs:

setup express app

// app.js

var exphbs = require('express-handlebars');
var helper = require('./helper');

/**
 * setup templating / rendering
 */
app.engine('hbs', exphbs({
  defaultLayout: 'default',
  extname: 'hbs',
  helpers: helpers(app)
}));

and a helper module combining all of my helpers:

// helpers.js

/**
 * hbs helpers get invoked by rendering
 * a template. They get the res.locals as
 * context in `this`
 */
module.exports = function(app) {
  return {

    /**
     * a basic form helper to render input fields
     */
    input: function(field, opt) {
      opt = opt.data ? {} : JSON5.parse(opt);
      var value = this.formdata ? this.formdata[field] || '' : '';
      var hasError = this.formerror && this.formerror[field];
      var ErrorMsg = hasError ? '<span class="help-block">' +
        this.__(
          this.formerror[field].msg,
          this.__('field.' + field),
          this.formerror[field].value
        ) +
        '</span>' : '';

      return `
          <div class="form-group ${hasError? 'has-error':''}">
            <label for="${field}">${this.__(opt.label || 'field.' + field)}</label>
            <input type="${opt.type || 'text'}"
              class="form-control"
              id="${field}"
              name="${field}"
              value="${value}">
            ${ErrorMsg}
          </div>`;
    }
  }
};

so a view could read like so:

    <form>

        {{{ input 'username' }}}
        {{{ input 'password' "{type: 'password'}" }}}

        {{> alerts/formerrors}}

        <div class="text-center">
            <button type="submit" class="btn btn-primary btn-block">{{__ 'Sign In' }}</button>
        </div>

    </form>