promise then code example

Example 1: promise js

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.
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Make a simple example.
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var asyncronus_function= (number)=>
		{
			return new Promise( (accept, reject)=>
			{
			})
		}                 
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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()
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Let complete asyncronus_function
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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]
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how we can retrieve accept or reject?
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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]
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let call asyncronus_function()!!! 
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	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!

Example 2: js return a promise

function myAsyncFunction(url) {
  return new Promise((resolve, reject) => {
    const xhr = new XMLHttpRequest();
    xhr.open("GET", url);
    xhr.onload = () => resolve(xhr.responseText);
    xhr.onerror = () => reject(xhr.statusText);
    xhr.send();
  });
}

Example 3: nodejs promise then example

p.then(onFulfilled, onRejected);

p.then(function(value) {
   //  run
  }, function(reason) {
  // fail
});

Example 4: .then javascript

const promise2 = doSomething().then(successCallback, failureCallback);