es6-promise

I've grown used to promise chaining arrays. It's incredibly easy to read a promise chain when each promise is a line long such as myArray.map(x => convertX) .filter() .whatever() .etc() This is incredibly easy to read. However, when I create promise chains with custom functions, it gets much messier. database.query(first query) .then(results => { // do stuff // do more // even more return database.query(second query) }) .then(results => { // rinse and repeat }) .catch(err => { // error handling }) Now, this can be legible, but when the promise chain extends further, it gets to be a little much

Let’s say I have a function foo which returns a promise. Is there a way to call the function, and optionally Promise.prototype.catch the result only if the rejection is unhandled? I want a solution which works in both node.js and the browser. For example: const fooResult = foo(); // pass fooResult somewhere else where fooResult may be caught with catch catchIfUncaught(fooResult, (err) => { console.log(err); // should be foo rejection only if the rejection is not caught elsewhere // no unhandled rejection occurs }); No, there is not. When your function returns a promise, that leaves error

I am using fetch api for fetching an URL that might return: Response : status = 200, json body = {'user': 'abc', 'id': 1} or Response : status = 400 , json body = {'reason': 'some reason'} or Response : status = 400 , json body = {'reason': 'some other reason'} I want to make a separate function request() that I use from various parts of my code as follows: request('http://api.example.com/').then( // status 200 comes here data => // do something with data.id, data.user ).catch( // status 400, 500 comes here error => // here error.reason will give me further info, i also want to know whether

If I am doing an async call like the following, how can chain them with promises, so i can do stuff in order? In this example, what ends up happening is that arr will push the items out of order. I'd prefer an answer with promises, but anything will do as long as it works var fbArrOfAlbumNames = ['Profile Pictures', 'Cover Photos', 'Mobile Uploads']; var arr = []; for(var x = 0; x < fbArrOfAlbumNames.length; x++) { (function(cntr) { FB.api('/' + fbArrOfAlbumNames[cntr] + '/photos/', {fields: 'picture,album'}, function(response) { arr.push(response); } })(x); } Assuming your ajax calls can

I am new to JavaScript and very new to node.js framework, just started using it a few days ago. My apologies if my code is nonsensical, the whole idea of promises and callbacks is still sinking in. That being said my question is the following I am trying to figure out if certain request to websites are successful or cause an error based on the range of their status code response. I am working with an array of websites and what I've done so far is below, I do however get a TypeError: Cannot read property 'then' of undefined on my local machine with node.js installed and can't figure out why.

I have constructed a function which iterates through a Generator containing both synchronous code and Promises : module.exports = { isPromise (value) { return typeof value === 'object' && value !== null && 'then' in value; }, runGen (generatorFunc, startValue) { let that = this, i = 0; function *iterator(resolve, reject) { let runGeneratorFunc = generatorFunc(startValue), yieldedOut = {done: false}, yieldIn; while (!yieldedOut.done) { console.log(i++, 'Ready for next iteration'); if (that.isPromise(yieldedOut.value)) { console.log(i++, 'Pass promise to KeepIterating'); yieldIn = yield