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what is a promise

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Mysterious Monkey answered on April 30, 2020 Popularity 10/10 Helpfulness 3/10

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what is a promise

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// Promise is a special type of object that helps you work with asynchronous operations.
// Many functions will return a promise to you in situations where the value cannot be retrieved immediately.

const userCount = getUserCount();
console.log(userCount); // Promise {<pending>}

// In this case, getUserCount is the function that returns a Promise. If we try to immediately display the value of the userCount variable, we get something like Promise {<pending>}.
// This will happen because there is no data yet and we need to wait for it.

Popularity 10/10 Helpfulness 3/10 Language javascript

Source: learn.coderslang.com

Tags: javascript promise

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Contributed on Feb 11 2021

Mysterious Monkey

0 Answers Avg Quality 2/10

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javascript promise

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let conditions=true;


const proms= new Promise((resolve, reject) => {
    setTimeout(() => {
        if (conditions) {
            resolve ("Hello")
        } else {
            reject ("This condition faild")
        }
    }, 2000);
});


proms.then((result) => {
    console.log(result);
})
.catch(function(error){
    console.log(error);
});

Popularity 10/10 Helpfulness 4/10 Language javascript

Source: Grepper

Tags: javascript j

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Contributed on Jul 18 2022

Noor Mohammad Patwary

0 Answers Avg Quality 2/10

is promise

Comment

import isPromise from 'is-promise';

isPromise(Promise.resolve());//=>true
isPromise({then:function () {...}});//=>true
isPromise(null);//=>false
isPromise({});//=>false
isPromise({then: true})//=>false

Popularity 9/10 Helpfulness 4/10 Language javascript

Source: github.com

Tags: javascript j

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Contributed on Apr 30 2020

Disgusted Dugong

0 Answers Avg Quality 2/10

what is promise in javascript

Comment

Promises are used to handle asynchronous operations in JavaScript.
They are easy to manage when dealing with multiple asynchronous operations
where callbacks can create callback hell leading to unmanageable code.

Popularity 10/10 Helpfulness 4/10 Language javascript

Source: Grepper

Tags: javascript j

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Contributed on May 20 2022

Raviraj Solanki

0 Answers Avg Quality 2/10

javascript promise

Comment

let promise = new Promise((resolve,reject)=>{
                try {
                    resolve("some data");
                } catch (error) {
                    reject(error);
                }
            })
            
            promise.then(function (data) {
                console.log(data);
            },function (error) {
                console.error(error);
            })

Popularity 10/10 Helpfulness 4/10 Language javascript

Source: stickynotepickles.herokuapp.com

Tags: javascript j

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Contributed on Feb 18 2022

Powerful Pigeon

0 Answers Avg Quality 2/10

promise javascript

Comment

let promise = new Promise(function(resolve, reject){
  try{
  	resolve("works"); //if works
  } catch(err){
    reject(err); //doesn't work
  }
}).then(alert, console.log); // if doesn't work, then console.log it, if it does, then alert "works"

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Source: Grepper

Tags: javascript j

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Contributed on Jul 22 2021

Unusual Unicorn

0 Answers Avg Quality 2/10

promise javascript

Comment

let num = 10;
//call back function
const promis = new Promise(function (resolve, reject) {

  if (num > 5) {

    //this resolve method will send data to resoleveData variable
    resolve(" Problem resolved successfully")
  }
  else {
    //this reject method will send data to rejectData variable
    reject("sorry problem couldn't solve")
  }

})
//resoleveData variable
promis.then(function (resolveData) {

  console.log(resolveData)
  //rejectData variable
}).catch(function (rejectData) {

  console.log(rejectData)
})

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Source: Grepper

Tags: javascript j

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Contributed on Dec 21 2021

SkiLL3r

0 Answers Avg Quality 2/10

js promise

Comment

const executorFunction = (resolve, reject) => {
  if (someCondition) {
      resolve('I resolved!');
  } else {
      reject('I rejected!'); 
  }
}
const myFirstPromise = new Promise(executorFunction);

Popularity 10/10 Helpfulness 3/10 Language javascript

Source: Grepper

Tags: javascript j

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Contributed on Sep 16 2021

0xTony143

0 Answers Avg Quality 2/10

promise js

Comment

We use promise to make a  AsyncFunction, cose simetime we have to wait that function give 
us some result.
Example, if we use ajax we have await ajax data or statament.
_____________________________________
Make a simple example.
_____________________________________
var asyncronus_function= (number)=>
		{
			return new Promise( (accept, reject)=>
			{
			})
		}                 
_____________________________________
this function return a promise Object, thet required a function executor
this functions (accept, reject) are defined in the executor 
function, that was needed in promise constructor.
Syntax: new Promise (executor)
executor= (accept, reject) =>{}

if function end well we return a accept(), otherwise reject()
_____________________________________
Let complete asyncronus_function
_____________________________________
var asyncronus_function= (number)=>
		{
			return new Promise( (accept, reject)=>
			{
				if(number>10)
				return accept("my first async");
				return reject("my first async error")
			})

		}
if it dont return any of this 2 function, Promise state is [PENDING] ,
if return accept is [RESOLVED]  end if return reject is [REJECTED]
_____________________________________
how we can retrieve accept or reject?
_____________________________________
there is two methods really important, that we have to consider afther we call this function
1) .then(function(error){}) is call when promise state is [RESOLVED]
2) .error(function(error){}) is call when promise state is [REJECTED]
3) do nothing if [PENDING]
_____________________________________
let call asyncronus_function()!!! 
_____________________________________
	asyncronus_function(MY_NUMBER).then(function(data)
        {
			console.log(data)
    	}).catch(error => 
        {
      			console.log(error)
    	});
		
if  MY_NUMBER> 10 ,asyncronus_function print data : OUTPUT my first async
if MY_NUMBER<10 , asyncronus_function print error : OUTPUT my first async error
HOPE it halp and have a nice day!

Popularity 10/10 Helpfulness 3/10 Language javascript

Source: Grepper

Tags: javascript j

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Contributed on Oct 06 2020

Ax_Misaki_Mei

0 Answers Avg Quality 2/10

js promise

Comment

const prom = new Promise((resolve, reject) => {
  resolve('Yay!');
});
 
const handleSuccess = (resolvedValue) => {
  console.log(resolvedValue);
};
 
prom.then(handleSuccess); // Prints: 'Yay!'

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Source: Grepper

Tags: javascript j

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Contributed on Sep 21 2021

0xTony143

0 Answers Avg Quality 2/10

what is a promise

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