If Error

Helps automate error handling in Node.JS applications.

Install

npm install if-error

Source code is at https://github.com/jeffersoncarpenter/if-error.

Example

Async operations can often experience errors. These errors are endemic to the world at large, not due to bugs in the code. Still, we write boilerplate in the form of if (err) { return next(err) }, catching these relative low-level errors one by one. Because such errors are rare, they lead to subtle bugs that are difficult to track down.

var middleware = function (next) {
  return asyncOperation1(function (err, result1) {
    if (err) { return next(err); }
    return asyncOperation2(result1, function (err, result2) {
      if (err) { return next(err); }
      return asyncOperation3(result2, function (err, result3) {
        if (err) { return next(err); }
        return next(null, result3);
      });
    });
  });
};

This tiny library greatly increases the robustness of this boilerplate code. Rather than a boilerplate if statement, you declare your error handler - and then make boilerplate calls to it. If you use this style everywhere, err values will only appear in your logging code.

var handleErrWith = require('if-error');

var middleware = function (next) {
  var handleErr = handleErrWith(next);
  return asyncOperation1(handleErr(function (result1) {
    return asyncOperation2(result1, handleErr(function (result2) {
      return asyncOperation3(result2, hanldeErr(function (result3) {
        return next(null, result3);
      }));
    }));
  }));
};