Yii2 Chart Is Not Defined

I am trying to show some data on the chart while using Yii2. I have installed Yii2 Chart JS via the composer. Below is the code is taken from the documentation use practically\cha

Solution 1:

To display chart you must echo result of widget

echo Chart::widget([
    'type' => Chart::TYPE_BAR,
    'datasets' => [
        [
            'data' => [
                'Label 1' => 10,
                'Label 2' => 20,
                'Label 3' => 30
            ]
        ]
    ]
]);