an example of nested (structured) exception handling in node.js

gistfile1.js

Function.prototype.catchAsync = function (cb) {
  var self = this;
  self.errHandler = cb;
  return function () {
    if (err) {
      self.errHandler(err);
    } else {
      var args = Array.prototype.push([], arguments);
      args.shift();
      this(args);
    }
  }
};

Function.prototype.raiseTo = function (cb) {
  return this.onError(cb.errHandler);
};

function modifyFile(file, cb) {
  
  fs.readFile(file, (function (content) {

    // process content
    var newContent = processContent(content);

    fs.writeFile(file, newContent, cb);

  }).raiseTo(cb));
}

function main(files) {
  var numProcessed = 0;
  var numErrors = 0;

  // start modifying all files in parallel
  for (var i = 0; i < files.length; i++)
    modifyFile(files[i], (function () {

      if (++numProcessed == files.length)
        process.exit(numErrors == 0 ? 0 : 1);

    }).catchAsync(function (err) {

      console.log(log);
      numErrors++;
      this(); // continue (by executing the callback right above)

    });
}