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Promise and one strange behaviour [closed]

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I encountered a strange behavior when I defined 4 Promises which the last one is described as just rejected and when I tried to run each promise separately, the last one is fired! This will fire rejection especially when I want to run all Promises (_1 _2 _3) in Promise.all().
I wanted to use catch() for promise_2 in Promise.all([promise.catch((err)=>console.log(err))]).then(...) from handling the error happend in promise_2 without cancelling the operation of other Promises
Thx
const asyncFunction=(timer,callback)=>{
setTimeout(() => {
callback(10)
}, timer);
}
const promise_1=new Promise((resolved,reject)=>{
const date=new Date().getSeconds()
date%2===0?asyncFunction(1000,(value)=>resolved(value)):reject(new Error("hello"))
})
const promise_2=new Promise((resolved,reject)=>{
asyncFunction(2000,(value)=>resolved(value))
})
const promise_3=new Promise((resolved,reject)=>{
asyncFunction(3000,(value)=>resolved(value))
})
const promise_4=new Promise((resolved,reject)=>{
reject(new Error("i am bad"))
})
promise_1.then((value)=>console.log(value))
first in Node
C:\Program Files\nodejs\node.exe .\test.js
Process exited with code 1
Uncaught Error Error: I am bad<--------------------------what is it?this is for promise_4 ,while I didn't call it
second in V8
See here
[in V81

Should a Javascript function avoid reject a promise via a ternary condition? [closed]

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I saw a piece of code that looks funny to me. It feels like there are multiple things wrong here. Am I seeing a ternary here returning an error rather than a value? Shouldn't this therefore be an if-else?
const aData = await response.json();
return await new Promise((resolve, reject) => {
(aData.title === aName)
? resolve('A data was found')
: reject(new Error('Incorrect data was returned'));
});

Both resolve and reject just return the value undefined, and your callback function doesn't return anything at all. Using a ternary operator to make it a single expression is rather useless.
For clarity, you should better write
if (aData.title === aName) resolve('A data was found');
else reject(new Error('Incorrect data was returned'));
although really you shouldn't be using the new Promise constructor here at all. Just
const aData = await response.json();
if (aData.title !== aName) throw new Error('Incorrect data was returned');
else return 'A data was found';

Is Nesting Promises Bad Practice? [closed]

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I know my code has the correct logic, but everywhere I look I'm told not to use nested promises. Is this a use case for nested promises?
The logic is as follows:
promise1 fails -> reverse promise1
promise1 succeeds -> promise2/promise3 fails -> reverse promise1,
promise2, promise 3
promise1 succeeds -> promise2 & promise3 succeeds
let data = null;
promise1.then((response) => {
data = response;
return Promise.all([promise2(), proimse3()])
.catch((error) => {
//Reverse only promise2, promise3
//Throw error to reverse promise1
});
}).then((id) => {
something(data);
}).catch((error) => {
//Reverse only promise1
});

Javascript scope in promises [closed]

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How can I access to the user object in the promises callback ?
I try to bind it with no success.
const promises = User.find(req.user._id).exec();
promises.then(function (user) {
noAccessFunction().then(function (customer) {
// HERE
user.save();
});
});

Promises are not callbacks! Mutate it as if it were a chain of values. Maybe something like this:
const promises = User.find(req.user._id).exec();
promises.then(function (user) {
return myfunction().then(function (customer) {
return user.save();
});
});
Promises can also be flattened:
const promises = User.find(req.user._id).exec();
promises.then(function (user) {
return myfunction(user);
})
.then(function (customer) {
return customer.save();
});
In any case the code above is speculation since you have not provided enough information as to what you want to happen.

Define Promise As ES6 Class Method [closed]

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Using ES6 syntax to define a class and its methods, how can I define a method as a Promise, without having to wrap it in a regular function that returns a promise? I want to do something like the following below:
class PromiseMethod {
promiseMethod = new Promise(function(resolve, reject) {
return resolve();
}
}

Promises are just an object returned from a function — whether it be a method or not doesn't matter. Try this:
class Something {
promiseMethod () {
return new Promise(...);
}
}
(new Something).promiseMethod().then(...)
But maybe you wanted to not have to call the method and be able to use the Promise methods directly? In this case, it's not a method, it's a property:
class Something {
constructor () {
this.promiseProperty = new Promise(...);
}
}
(new Something).promiseProperty.then(...);