Yii2 Add a Form field not in model - yii2

Question

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 ?

Answer 1

The Html class contains the functions for generation of fields. In fact, your code above ends up calling Html::textInput(). To add a field
<?= Html::textInput("name", $value) ?>
To add javascript to a view just use registerJs():
$this->registerJs("alert('true');");

Answer 2

You can have the field rendered the same way as the ActiveField, with a label and classes. For example, let’s add a Cc field to a Mail form.
First display the To: field (in the model):
<?= $form->field($model, 'to')->textInput() ?>
Let’s add the Cc field (not in the model):
<?= Html::beginTag('div', ['class' => 'form-group field-mail-cc']) ?>
<?= Html::label('Cc:', 'mail-cc', ['class' => 'control-label']) ?>
<?= Html::textInput('Mail[cc]', '', ['id' => 'mail-cc', 'class' => 'form-control']) ?>
<?= Html::endTag('div') ?>
The class and id names mail-cc and field-mail-cc follow the ActiveForm naming pattern. The input name Mail[cc] adds your field to the ActiveForm group, so you can easily retrieve it with the usual
$form = Yii::$app->request->post('Mail');