Как повесить focus на первый input в форме?

Как повесить фокус на первое поле, которое будет отображено после изменения в форме?

(function(factory) {
if (typeof define === 'function' && define.amd) {
    define([
        'common.views.SimpleView',
        'login.views.LoginView',
        'login.views.RestorePasswordView',
        'underscore'
    ], factory);
} else {
    factory();
}
})(
function(SimpleView, LoginView, RestorePasswordView) {
    var LoginPageView = SimpleView.extend({
        el: ".loginPageView",
        initialize: function() {
            this.createHandle();
            this.loginView = new LoginView({
                handle: this.handle,
                steps: ['step-login', 'step-sms'],
                onRender : function () {
                }
            });
            this.restorePasswordView = new RestorePasswordView({
                handle: this.handle,
                steps: ['step-email', 'step-sms', 'step-restore', 'step-
 complete']
            });
            this.render();
        },
        render: function() {
            this.$el.append(this.loginView.el);
            this.$el.append(this.restorePasswordView.el);
            this.delegateEvents();
            return this;
        },
        _doHandle: function(event, opts) {
            if ('goToLogin' == event) {
                this.loginView.$el.removeClass("hidden");
                this.restorePasswordView.$el.addClass("hidden");
                this.loginView.clearAll();
            }
            if ('goToRestorePassword' == event) {
                this.loginView.$el.addClass("hidden");
                this.restorePasswordView.open();
            }
            if ('goToSms' == event) {
                this.restorePasswordView.$el.addClass("hidden");
                this.loginView.$el.removeClass("hidden");
                this.loginView._changeStep({isNext: true});
            }
            if ('goToChangePassword' == event) {
              this.loginView.$el.addClass("hidden");
            });
    new LoginPageView();
}
);