<strong>This is the first line
This is the second line</strong>
var myString = "This is the first line \n This is the second line";
If you want to have the new line in html you need some element like
<br />. In fact, each block styled element will do, but
<br /> wont add any margin/padding by default, as f. i. a
<h3> would. Anyway, breaking a line html requires any element, since "\n", "\t" and so on are ignored by the browser.