Styled alert box without a JS library

I would like to 开发者_开发技巧display an alert on my web site. I could use a library like jQuery, but currently, the site does not use one, and I don't think it is a good idea to add a library just for the sole purpose of an alert box.

Is there any way of styling the alert box, or is there a pure js alternative to something like jQuery modal dialog?

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Is there any way of styling the alert box

No, it is browser chrome and you can't touch it.

or is there a pure js alternative to something like jQuery modal dialog?

jQuery doesn't have a modal dialog. jQuery UI does.

There is no pure JS alternative — you are dealing in presentation, so you need CSS.

jQuery UI is pure JS + CSS, and anything you can do with it, you can do by writing the JS and CSS yourself. Look at their code if you want an example.