javascript - Series of async ajax calls inside a series of async ajax calls. How to know when all calls are finished? -

so have 'for' on each iteration calls different ajax call, in callback of each call collect urls , run ajax call each url.

it looks

for(var i=1; i<num_pages + 1; i++) {      var page_url = main_url + "&sf=" + i;      console.log('=== doing page: ' + page_url);      try     {         $.ajax({url: page_url, async:false, success: function(data)          {              var urls = [];              $('a', data).each(function()             {                 if($(this).attr('itemprop') == 'url')                 {                     var u = $(this).attr('href');                     if(urls.indexof(u) == -1)                     {                         urls.push(u);                     }                 }             });              // for(var j=0; j<urls.length; j++)             for(var j=0; j<3; j++)             {                 dosettimeout(j, i);             }         }          });     }     catch(err)     {      } }  function dosettimeout(i, page_num)  {   settimeout(function()    {      get_info(urls[i], page_num);   }, 100); } 

dosettimeout() used have delay of 100ms between calls get_info(), info a function containing async ajax call.

i them async try not overload server requests, , because tried find order know when finishes, doesn't work.

as it's async jquery's ajaxstop triggers after every single ajax done.

not sure how promises either.

help appreciated.

edit: here's how get_info looks like:

function get_info(url, page_num) {     $.ajax({ url: url, async: false, success: function(data)          {              // optional, it's true it's false             if(views_enabled)             {                 $.ajax({type:'post', async:false, url:'/someurl/', data:{price: price}, success: function()                 {                     item['views'] = data.views;                     all_data.push(item);                     console.log('finished item');                 }                 });              }             else             {                  console.log('finished item');             }         }      }); }