itera
itera for promise iteration needs. Mix generators and promises for better control flow. Made this for my personal workflow. Most likely co will be a better solution for you.
If you do not understand JavaScript generators see:
Example
NOTE:
Below step1() step2() step3() functions all return promises. See tests code for full implementation of below generator logic.
Plus, itera-sample is a simple project showing itera in action.
const Generator = function * () {
// ERRORS AND YIELDING PROMISES
// if a promise executes and resolves with an error.
// The value of the error resolution "reject()" is placed in the
// variable associated with the yield.
const result1 = yield step1();
if (result1 instanceof Error) {
// console.log(typeof result1);
// console.log(result1.message);
// console.log(result1.name);
// console.log('ERROR');
return callback(result1, null);
}
// result1 yield SUCCESS DO STUFF with result1
console.log(result1);
const result2 = yield step2();
if ( (result2.name !== undefined) && (result2.name === 'Error')) {
// HANDLE THE ERROR
// console.log(result2.message);
// console.log(result2.name);
console.log('ERROR');
return; // exit the generator.
}
console.log(result2);
// return; exits generator early if error exists.
const result3 = yield step3();
if ( (result3.name !== undefined) && (result3.name === 'Error')) {
// console.log(typeof result3);
// console.log(result3.message);
// console.log(result3.name);
// console.log(result3);
console.log('ERROR');
}
console.log(result3);
return;
};
const callback = function (err, result) {
// do stuff after generator is complete.
};
Itera(Generator, callback);
Credits
JavaScript Ninja Second Edition p. 159 listing-6.19.html
- reworked the async() to implement my preferences on error handling and to get the code ready for use in my projects.
- Authors: John Resig, Bear Bibeault, Josip Maras
- some inspiration came from co too.
- Authors: @tjholowaychuk & @jonathanong
;-)