Created
January 7, 2015 18:14
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$.Deferred vs new Promise vs Callbacks - be careful you are not rebuilding the hell
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// consider the following code | |
function getInfoDef() { | |
var result = {something: 'static'}; | |
var def = $.Deferred(); | |
$.ajax('/some-url').then(function(data) { | |
result.also = data.dynamic; | |
def.resolve(result); | |
}).fail(def.reject.bind(def)); | |
return def.promise(); | |
} | |
// if you are like me (half a year ago) you probably think this is just fine | |
// however, lets rewrite the same using ES6 Promises | |
function getInfoES6() { | |
return new Promise(function(resolve, reject) { | |
var result = {something: 'static'}; | |
$.ajax('/some-url').then(function(data) { | |
result.also = data.dynamic; | |
resolve(result); | |
}).fail(reject); | |
}); | |
} | |
// notice the extra level of indentation? | |
// does it remind you of callback hell? | |
// that's because it still is the same inversion control | |
function getInfoCB(callback) { | |
var result = {something: 'static'}; | |
$.ajax('/some-url').then(function(data) { | |
result.also = data.dynamic; | |
callback(null, result); | |
}).fail(callback); | |
}); | |
} | |
// this is how you should do it | |
function createThingy(remoteData) { | |
return { | |
something: 'static', | |
also: remoteData.dynamic | |
} | |
} | |
function getInfo() { | |
return $.ajax('/some-url').then(createThingy); | |
} |
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