You have to assign the return value of .then back to chain: chain = chain.then(()=>getProm(i)) .then(Wait) Now you will basically be doing chain .then(()=>getProm(1)) .then(Wait) .then(()=>getProm(2)) .then(Wait) .then(()=>getProm(3)) .then(Wait) // … instead of chain .then(()=>getProm(1)) .then(Wait) chain .then(()=>getProm(2)) .then(Wait) chain .then(()=>getProm(3)) .then(Wait) // … You can see that the first one is actually a chain, … Read more
In Browsers First of all no – there is no built in for this. Lots of libraries that enhance ES2015 promises like bluebird whip with it. I think the other answer conflates executing the function and a delay, it also creates timeouts that are impossible to cancel. I’d write it simply as: function delay(ms){ var … Read more
Update Dec 11 – 2016: All evergreen versions of browsers now support promises. They are safe to use. Update Nov 14 – 2016: Chrome, Firefox, Safari and IE all now have experimental support for promises in their dev channels. The specification has settled. I would still not rely on the implementation just yet and would … Read more
An easy function to use and understand for some async replace : async function replaceAsync(str, regex, asyncFn) { const promises = []; str.replace(regex, (match, …args) => { const promise = asyncFn(match, …args); promises.push(promise); }); const data = await Promise.all(promises); return str.replace(regex, () => data.shift()); } It does the replace function twice so watch out if … Read more
I’ve knocked up a little helper function that you can re-use. Basically pass your promises as normal, and provide a callback to do what you want with the progress.. function allProgress(proms, progress_cb) { let d = 0; progress_cb(0); for (const p of proms) { p.then(()=> { d ++; progress_cb( (d * 100) / proms.length ); … Read more
ES6 supports destructuring, so if you just want to name the results you can write: var myFuncAsync1 = () => Promise.resolve(1); var myFuncAsync2 = () => Promise.resolve(2); Promise.all([myFuncAsync1(), myFuncAsync2()]) .then(([result1, result2]) => console.log(result1 +” and “+ result2)) //1 and 2 .catch(e => console.error(e)); Works in Firefox and Chrome now.
What is the difference between observables and promises? Simply put: A promise resolves to a single value asynchronously, an observable resolves to (or emits) multiple values asynchronously (over time). Concrete examples: Promise: Response from an Ajax call Observable: Click events More information can be found here: http://reactivex.io/intro.html i’ve read that observables are looking to overtake … Read more
You can pull in the Babel polyfill by simply installing Babel Polyfill: npm install –save-dev babel-polyfill and then include the polyfill file before your source and test files within the files section of your karma.conf.js: files: [ ‘node_modules/babel-polyfill/dist/polyfill.js’, ‘index.js’, //could be /src/**/*.js ‘index.spec.js’ //could be /test/**/*.spec.js ], Unless you know that all your target browsers … Read more
jQuery Ajax methods return promises themselves, you don’t need to wrap them at all. But you can, of course, do it for consistency with the ES6 promise API. UPDATE jQuery 3.0+ implements the Promise/A+ API, so there is no reason anymore to wrap anything in modern jQuery. Read up on the peculiarities of jQuery’s promise … Read more
No. Not only will .done likely not be supported in the future versions of the spec – it is unneeded. Quoting from the threads Mariusz linked to: Domenic: it’s still error-prone: if you slip up and don’t follow the rule even once, you might silence an error forever. Mark Miller (who pioneered the concept of … Read more