When I run the following code,I see an alert box with bold 'Code Playground' written at the top.How do I code for it?

Question

alert("Do you really want to leave this page?");

Answer 1

I would love to.If you have downloaded the app,you would know alert boxes show something more than just the encoded words.These words appear in block at the top.
As for example,when you try to open a module before finishing the earlier one,the alert box shows 'Module locked' in bold.How do we get that?