Multiple 'then' in Promises #894
Comments
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@gfwilliams, I'm not sure problem is completely fixed. function onInit() {
var promise = new Promise(function (resolve) {
setTimeout(resolve, 1000);
});
promise.then(function () {
console.log('first');
promise.then(function () {
console.log('third');
});
});
promise.then(function () {
console.log('second');
});
setTimeout(function () {
console.log('ready for fourth promise');
promise.then(function () {
console.log('fourth');
});
}, 1500);
}
save(); // just hackWill output: Fourth callback will never called. Few more cases. function onInit() {
var promise = new Promise(function (resolve) {
setTimeout(resolve, 1000);
});
promise.then(function () {
console.log('first');
promise.then(function () {
console.log('third');
});
});
/*promise.then(function () {
console.log('second');
});*/
setTimeout(function () {
console.log('ready for fourth promise');
promise.then(function () {
console.log('fourth');
});
}, 1500);
}
save();And output: Third callback will never called, same as fourth. function onInit() {
var promise = new Promise(function (resolve) {
setTimeout(resolve, 1000);
});
promise.then(function () {
console.log('first');
promise.then(function () {
console.log('third');
});
});
promise.then(function () {
console.log('second');
});
setTimeout(function () {
console.log('ready for fourth promise');
promise.then(function () {
console.log('fourth');
});
}, 500); // decreased timeout for chaining with promise before it resolves
}
save();Output will be correct: upd: firmware 1v99, esp32 |
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Thanks, I created an issue for it ^^^ Basically this is when you call If you want to work around it, just add all the Did you actually hit this in real-life code, or were you running through some tests? |
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Yes, I use Promises in my code. But I can imagine how difficult and costly is to make realization of Promise in Espruino(utilization and other). I can deal without Promises of course, but It will be more verbose code. I suppose, if promises can't be realized natively it should be removed and if some one will need it Promises can be written on JS directly(can't imagine how costly on controller it will be). Promises is really important thing in JS, for example to make |
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If you use a new Espruino build from travis, those issues that you found should now be fixed. They'll be sorted in 1v100 anyway |
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Thank you, I tested, order is correct, works great! function foo(bar) {
console.log(bar);
}
function onInit() {
const promise = new Promise(function(resolve, reject) {
// setTimeout(() => reject('OK'), 100);
// # Normal behaviour
// setTimeout(() => resolve('OK'), 100);
// # Normal behaviour
// setTimeout(reject.bind(undefined, 'OK'), 100);
// # Never executes 'promiseRejected' and event 'promiseCatch'
// # Exception gets: 'Uncaught Error: Unhandled promise rejection: OK'
// setTimeout(resolve.bind(undefined, 'OK'), 100);
// # Never resolves
// # No errors
});
promise.then(
function promiseSucceeded(result) {
console.log(`Resolved: ${result}`);
},
function promiseRejected(error) {
console.log(`Error: ${error}`);
}
);
promise.catch(function promiseCatch(catched) {
console.log(`Catched: ${catched}`);
});
}
save();Just uncomment one of resolve or rejection lines. So, |
Looks like there's a problem:
http://forum.espruino.com/conversations/290967/
Can't believe I didn't spot/test this at the time, but should be an easy fix.
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