The preferred way to install this extension is through composer.
$ composer require eddmash/yii2-clipboard "@dev"
You can use the widget which create a input that has copy button.
echo \Eddmash\Clipboard\Clipboard::widget([ 'model' => $model, 'attribute' => 'email', 'options'=>['readonly'=>""] ]);
Or if you need to use it without a model. The Clipboard::input() method is works like HTML::tag() actually its use it to create its output. The only difference is that it takes the first argument as the view object on which the output is being done.
$url = "https://packagist.org/packages/eddmash/yii2-clipboard"; Clipboard::input($this, 'text', 'url', $url, ['id' => 'url', 'readonly' => true])
Or if simply need the composer.js loaded on a view