node.js - Getting original request object during multiple asynchronous calls in nodejs-request -

i have multiple http requests in nodejs app each returns word of sentence. replies come @ different times, i'm saving them in dictionary, key being original sentence's word index. problem is, when access request object, last one.

var completed_requests = 0;  sentence = req.query.sentence; sentence = "sentence translated" responses=[]; words = sentence.split(" "); for(j=0;j<words.length;j++){     var word = words[j];     var data={         word:word     };     var options = {       url: 'example.com',       form:data,       index:j     };     request.post(options, function(err,httpresponse,body){         options = options;         if(!err){             responses.push({options.index: body});             completed_requests+=1;             if(completed_requests==words.length){                 var a="";                 for(var k=0;k<words.length;k++){                     a+=responses[k]+" ";                 }                 res.render('pages/index', { something: });             }         }         else{             //err         }     }); } 

basically, when access object.index object, object returned isn't 1 used original request, last 1 (for reason). how should resolve this?

when take @ how code evaluated javascript due it's async nature in node.js problem becomes obvious:

1. for first word loop for(j=0;j<words.length;j++){ executed.
2. the value of j assigned options.index. loop run options.index has value 0.
3. request.post(options, function(err,httpresponse,body){ executed callback handler invoked later.
4. for first word loop for(j=0;j<words.length;j++){ executed.
5. the value of j assigned options.index. options.index has value 1.
6. request.post(options, function(err,httpresponse,body){ executed callback handler invoked later.

the problem becomes obvious since no new options objects created value of j assigned options.index in every loop run. when first callback handler invoked options.index has value words.length - 1.

to fix problem wrap creating options object in function executerequest

var completed_requests = 0;  sentence = req.query.sentence; sentence = "sentence translated" responses=[]; words = sentence.split(" "); for(j=0;j<words.length;j++){     var word = words[j];     var data={         word:word     };      function executerequest(url, form, index) {         var options = {             url: url,             form: form,             index: index           };           request.post(options, function(err,httpresponse,body){               // options = options; superfluous               if(!err){                   responses.push({ [index]: body});                   completed_requests+=1;                   if(completed_requests==words.length){                       var a="";                       for(var k=0;k<words.length;k++){                           a+=responses[k]+" ";                       }                       res.render('pages/index', { something: });                   }               }               else{                   //err               }           });     }      executerequest('example.com', data, j); } 

a read scoping , hoisting in javascript can found here http://www.adequatelygood.com/javascript-scoping-and-hoisting.html