when multiple ajax calls done

Question

Following is the scenario which doesn't work in the order I want:

var masterData = {};
var tableNames = ['table1','table2','table3','table4','table5','table6'];
var pullSqlData = function(){
  tableNames.forEach(function(value) {
    if(storage.isEmpty(value)) {
      $.getJSON('http://domain.com?r=appsync/read&id='+value+ "&callback=", function(data){
        masterData[value] = data;
        storage.set(value,data);
      });
    } else {
      masterData[value] = storage.get(value);
    }
  });
};

$.when(pullSqlData()).done(function(){
console.log('all done');
});

After searching around I know I can get above to work if I manually do something like

$.when(
$.getJSON('http://domain.com?r=appsync/read&id=table1&callback=', function(data){
        masterData[value] = data;
        storage.set(value,data);
      }),
$.getJSON('http://domain.com?r=appsync/read&id=table2&callback=', function(data){
        masterData[value] = data;
        storage.set(value,data);
      }),
//more calls
).done(function(){
console.log('all done');
});

However I was wondering if there is a way of doing above the proper way

*storage is a HTML5 localStorage jQuery plugin

Answer 1

Since you are a dynamic number of requests, try

var masterData = {};
var tableNames = ['table1', 'table2', 'table3', 'table4', 'table5', 'table6'];
var pullSqlData = function () {
    var requests = [];
    tableNames.forEach(function (value) {
        if (storage.isEmpty(value)) {
            var xhr = $.getJSON('http://domain.com?r=appsync/read&id=' + value + "&callback=", function (data) {
                masterData[value] = data;
                storage.set(value, data);
            });
            requests.push(xhr)
        } else {
            masterData[value] = storage.get(value);
        }
    });
    return requests;
};

$.when.apply($, pullSqlData()).done(function () {
    console.log('all done');
});

You need to pass all the ajax requests to $.when() so pullSqlData has to return the list of ajax requests created by it. Also $.when() does not take an array as an arguments so you need to use Function.apply() to pass the variable number of parameters to it

Answer 2

Check with each success execution

var masterData = {};
var tableNames = ['table1', 'table2', 'table3', 'table4', 'table5', 'table6'];
var pullSqlData = function () {
    var requests = [];
    tableNames.forEach(function (value) {
        if (storage.isEmpty(value)) {
            var xhr = $.getJSON('http://domain.com?r=appsync/read&id=' + value + "&callback=", function (data) {
                masterData[value] = data;
                storage.set(value, data);
                check_if_all_done();
            });
            requests.push(xhr)
        } else {
            masterData[value] = storage.get(value);
        }
    });
    return requests;
};

function check_if_all_done()
{
   if(masterData.length == tableNames.length ) console.log('done');

}

Answer 3

Something like this should work to make the requests in order:

var requests = pullSqlData() //save in array of promises each request as @ArunPJhonny

var first = requests.shift();

        $.each(requests, function (n, p) {
            first.then(function () {
                return p;
            });
        });

        first.done(function () {
            //...done
        });