nestless v0.1.3

Nestless.js

Rewrites synchronous-style flattened JS into callback-y JS.

Sample input:

function cat(encoding, cb) {
    filename <- askUser("Filename? ");
    contents <- fs.readFile(filename, encoding);
    if (contents.match(/piracy/))
        throw "TAKEN DOWN";
    return contents;
}

becomes:

function cat(encoding, cb) {
    askUser("Filename? ", function (err, filename) { if (err) return cb(err);
    fs.readFile(filename, encoding, function (err, contents) { if (err) return cb(err);
    if (contents.match(/piracy/))
        return cb("TAKEN DOWN");
    return cb(null, contents);
}); }); }

The transformation is braindead but it will always preserve line numbers.

Every transformed function must take a last parameter called callback or cb and contain at least one arrow binding.

After the first arrow binding, any return or throw in the same function (not in contained functions!) will be transformed to a callback invocation. See the test folder for more examples.

WARNING

• Nestless is very dumb and hacky and comes without warranty. It only handles a certain (common) case. Do not use nestless-generated code for anything important without examining the transformed output.
• Loops are right out. Use async.js or TameJS or write it out manually.
• Once you return a value, nestless tries to stop all execution in the function by possibly inserting more returns. Strange control flows may break this. I assume no responsibility if your callback never gets called or, worse, gets called multiple times. Use yield instead of return if you want control flow to fall through.