Yii2 how to add ajax check for uniqueness of username and email fields?

Question

Yii

Here is the registration form:
<?php
$form = ActiveForm::begin();
echo $form->field($model,'username');
echo $form->field($model,'email');
echo $form->field($model,'password')->passwordInput();
echo $form->field($model,'repeatpassword')->passwordInput();
echo Html::submitButton('Reg');
ActiveForm::end();
?>

Answer 1

Ajax validation: https :
//github.com/yiisoft/yii2/blob/master/docs/g... g...