some advice of widget of activeForm

when i use the widget of activeForm(Yii2.0.4) and set like follow:

ActiveForm::begin([

'enableClientValidation' => true,


'enableAjaxValidation' => true,


...............

it seems "enableAjaxValidation" is working,but "enableClientValidation" is not work before ajax request is send.

hope u known what i mean is.