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    <p><strong>With a custom object</strong></p> <pre><code>function DeferredAjax(opts) { this.options=opts; this.deferred=$.Deferred(); this.country=opts.country; } DeferredAjax.prototype.invoke=function() { var self=this, data={country:self.country}; console.log("Making request for [" + self.country + "]"); return $.ajax({ type: "GET", url: "wait.php", data: data, dataType: "JSON", success: function(){ console.log("Successful request for [" + self.country + "]"); self.deferred.resolve(); } }); }; DeferredAjax.prototype.promise=function() { return this.deferred.promise(); }; var countries = ["US", "CA", "MX"], startingpoint = $.Deferred(); startingpoint.resolve(); $.each(countries, function(ix, country) { var da = new DeferredAjax({ country: country }); $.when(startingpoint ).then(function() { da.invoke(); }); startingpoint= da; }); </code></pre> <p>Fiddle <a href="http://jsfiddle.net/7kuX9/1/" rel="noreferrer">http://jsfiddle.net/7kuX9/1/</a></p> <p>To be a bit more clear, the last lines could be written</p> <pre><code>c1=new DeferredAjax( {country:"US"} ); c2=new DeferredAjax( {country:"CA"} ); c3=new DeferredAjax( {country:"MX"} ); $.when( c1 ).then( function() {c2.invoke();} ); $.when( c2 ).then( function() {c3.invoke();} ); </code></pre> <p><strong>With pipes</strong></p> <pre><code>function fireRequest(country) { return $.ajax({ type: "GET", url: "wait.php", data: {country:country}, dataType: "JSON", success: function(){ console.log("Successful request for [" + country + "]"); } }); } var countries=["US","CA","MX"], startingpoint=$.Deferred(); startingpoint.resolve(); $.each(countries,function(ix,country) { startingpoint=startingpoint.pipe( function() { console.log("Making request for [" + country + "]"); return fireRequest(country); }); }); </code></pre> <p><a href="http://jsfiddle.net/k8aUj/1/" rel="noreferrer">http://jsfiddle.net/k8aUj/1/</a></p> <p>Edit : A fiddle outputting the log in the result window <a href="http://jsfiddle.net/k8aUj/3/" rel="noreferrer">http://jsfiddle.net/k8aUj/3/</a></p> <p>Each pipe call returns a new promise, which is in turn used for the next pipe. Note that I only provided the sccess function, a similar function should be provided for failures.</p> <p>In each solution, the Ajax calls are delayed until needed by wrapping them in a function and a new promise is created for each item in the list to build the chain. </p> <p>I believe the custom object provides an easier way to manipulate the chain, but the pipes could better suit your tastes.</p> <p><strong>Note</strong> : as of jQuery 1.8, <a href="http://api.jquery.com/deferred.pipe/" rel="noreferrer"><code>deferred.pipe()</code></a> is deprecated, <a href="http://api.jquery.com/deferred.pipe/" rel="noreferrer"><code>deferred.then</code></a> replaces it.</p>
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    1. POHow to chain ajax calls using jquery
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    1. POHow to chain ajax calls using jquery
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    1. COThis answer definitely works, I'm trying to digest all of it as it is quite complex. Thank you!
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    2. COI think I'm seeing this now. The main difference between my original code and yours seems to be that you are creating Deferred objects for every request, where mine was trying to use a single Deferred. Am I correct?
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    3. COSome specific questions for you: (1) why do you explicitly return a promise when you are already returning the promise from the ajax call? (2) why are assiging "this" to "self"? (3) why did you not choose to use pipe() when that is the native jquery queue function? (4) When we are creating Deferred objects for each request, what is the memory requirement when I start feeding hundreds of requests into the "queue"? How lightweight is a Deferred object?
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