var s /*:String*/ = "Test \ multi \ line."; alert(s);
This is perfectly valid; the interpreter just ignores the slash and the line break. The output from this code snippet is “Test multi line.” Just goes to show, you can write books on a topic and still not know everything about it.
Disclaimer: Any viewpoints and opinions expressed in this article are those of Nicholas C. Zakas and do not, in any way, reflect those of my employer, my colleagues, Wrox Publishing, O'Reilly Publishing, or anyone else. I speak only for myself, not for them.