Created
September 19, 2016 13:18
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Example of an ordered processing of asynchronous event handled by asynchronous handlers (JavaScript / jQuery, Promise).
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<!DOCTYPE html> | |
<html lang="en"> | |
<head> | |
<meta charset="UTF-8"> | |
<title>Title</title> | |
<script src="https://code.jquery.com/jquery-1.9.1.min.js"></script> | |
</head> | |
<script> | |
/** | |
* Executes submitted jobs in order. | |
* | |
* Useful for async jobs. Async jobs should return a promise. | |
* After the promise is resolved, the next job will be executed. | |
* | |
* Use .submit(job) to add a new job. | |
* | |
* Example of a async job: | |
* | |
* executionChain.submit(function() { | |
* var deferred = $.Deferred(); | |
* setTimeout(function () { | |
* console.log('Completed'); | |
* deferred.resolve(); | |
* }, 2000); | |
* return deferred.promise(); | |
* }); | |
* | |
* @returns {ExecutionChain} | |
* @constructor | |
*/ | |
function ExecutionChain() { | |
var lastPromise = $.when(); | |
this.submit = function (job) { | |
if (!$.isFunction(job)) { | |
throw "not a function: " + job; | |
} | |
lastPromise = lastPromise.then(job, job); | |
}; | |
return this; | |
} | |
$(function () { | |
$('button[data-num]').on('click', function () { | |
var num = $(this).attr('data-num'); | |
fire(num); | |
}); | |
var chain = new ExecutionChain(); | |
function fire(num) { | |
log('Fired ' + num); | |
var func = function () { | |
return handler(num); | |
}; | |
if (num == 3) { | |
func = function () { | |
log('Sync handler 3 executed'); | |
}; | |
} | |
chain.submit(func); | |
} | |
function handler(num) { | |
var deferred = $.Deferred(); | |
log('Started ' + num); | |
setTimeout(function () { | |
if (num == 4) { | |
log('Failed ' + num); | |
deferred.reject(); | |
} else { | |
log('Completed ' + num); | |
deferred.resolve(); | |
} | |
}, 2000); | |
return deferred.promise(); | |
} | |
function log(msg) { | |
var $console = $('#console'); | |
$console.val($console.val() + '\n' + msg); | |
} | |
}); | |
</script> | |
<body> | |
<button data-num="1">Fire 1 async</button> | |
<button data-num="2">Fire 2 async</button> | |
<button data-num="3">Fire 3 sync</button> | |
<button data-num="4">Fire 4 fail</button> | |
<label>Console:</label> | |
<textarea id="console" style="width: 400px; height: 400px;"></textarea> | |
</body> | |
</html> |
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