Is there any attempt to bring async/await feature from C# 5.0 to any language which can be compiled to JavaScript (such as CoffeScript)? (So it can be used
Yes there is, and you don't even need to compile it, because it is just a simple JavaScript library.
One of my projects called sharpnr.js has the aim to extend JavaScript with great features of C# (and .NET of course) like await/async, or LINQ.
The library is currently in beta, but it's stable and supports almost every statement (for example loops, switch, if), and works well with existing libraries (like jQuery).
The await/async syntax is almost identical to the C# version:
var getAsync = async(function(url) {
var result = await; $.get(url);
$("#test").html(result);
});
getAsync("http://www.sharpnrjs.com");
Working example on jsfiddle.
You can download the library from github.