I have a button using the following code in my view...
<?= Html::submitButton('Delete Summary', [
            'class' => 'btn btn-danger',
            'data' => [
                'confirm' => 'Really long message.<new line>Line 2<new line>Line 3?',
                'method' => 'post',
            ],
        ]) ?>
I want to make the eventual confirmation dialog show my text on different lines, but none of the common notations such as \n, <br>, nor 

 work. I also tried putting \\n instead of \n, still it did not work.
How can I make the different parts of my confirmation show on a different line.