As we know,
<?= $form->field($model, 'name_field')->textInput() ?>
Adds a text field connected to 'name_field' in the model/table.
I want to add a field NOT in the model/table, and then run some JS when it loses focus to calculate the other fields.
How firstly do you add a free text field not connected to the model ? Second, does anyone have any examples of adding JS/Jquery to the _form.php ?
ActiveRecord-instance but put a special form-model in between (can be a simpleModel), especially for that sort of things. You can add as many custom fields as you want, add special form-only validation rules.