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copied!<p>I see I'm late, but anyway:</p> <p>When putting a function in a loop, or recursion, variables in closures are evaluated at the time the function is executed, not when it is created. So</p> <pre><code>for (i in [1, 2, 3]) { setTimeout(function() { console.log(i); }, 1000); } </code></pre> <p>returns</p> <pre><code>3 3 3 </code></pre> <p>but</p> <pre><code>for (i in [1, 2, 3]) { setTimeout(function(i) { return function() { console.log(i); }; }(i), 1000); } </code></pre> <p>will correctly give you</p> <pre><code>1 2 3 </code></pre> <p>This is why it is generally not recommended to put function definitions in a loop.</p> <p>Anyway, here is corrected code for you, note it console.logs everything in correct order:</p> <pre><code>var http = require('http'); var querystring = require('querystring'); var myArr = [1,2,3,4,5,6,7,8,9,10,11,12]; function requestSender(d, callback) { var post = querystring.stringify({ data: d }); var options = { hostname: 'www.example.com', port: 80, path: '/upload', method: 'POST' }; var req = http.request(options, function(res) { res.setEncoding('utf-8'); res.on('data', function(data) { console.log(d); console.log(data); callback(); }); }); req.on('error', function(e) { console.log('problem with request: ' + e.message); }); req.write(post); req.end(); } function stack(arr) { var newArr = arr.slice(1); arr[0](function(arg) { return function() { if (arg.length > 0) stack(arg); }; }(newArr)); } var functionsArr = []; for (i in myArr) { functionsArr.push(function(i) { return function(callback) { var value = myArr[i]; requestSender(value, callback); }; }(i)); } stack(functionsArr); </code></pre>

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