Promises: Early Return

promisesEarlyReturn.js

// const ...
var EARLY_RETURN;

function _getSomething(key, data) {
    var scopedResult;

    return cache.fetchSomething(key)
    .then(function(_resolved) {
        scopedResult = _resolved;
        if (scopedResult) {
            // no need to create what we can fetch
            throw EARLY_RETURN;
        }

        return _createSomething(data);
    })
    // ...
    .then(function(_resolved) {
        scopedResult = _resolved;

        return cache.putSomething(key, _resolved);
    })
    .catch(function(err) {
        if (err !== EARLY_RETURN) {
            // oh, that's an Error fo real
            throw err;
        }
    })
    .then(function() {
        return scopedResult;
    });
}