AJAX functions called sequentially - php

Question

Excuse me. I'm still learning the amazing JQuery language. I've faced a problem, read a lot, and still in a mess. Hope you can guide me through the solution.
I have three functions which perform three post calls. They return a text var which I lately parse as a JSON if available.
<script>
$(document).ready(function() {
...
afterAction:
a(param1,param2);
...
param1: [other value];
...
b(param1);
select:
a(param1,param2);
b(param1);
...
});
function a (param1,param2) {
// get data from DOM objects, val, texts, whatever
$.post ( "a.php", {
param1: param1,
param2: param2,
stuff1: [data from DOM objects...]
},function(data){
console.log(data)
// do something (change dom objects properties, append..)
}
});
function b (param1) {
// get data from DOM objects, val, texts, whatever
$.post ( "b.php", {
param1: param1,
stuff1: [data from DOM objects...]
},function(data){
console.log(data)
// do something (change dom objects properties, append..)
}
});
function c (param1) {
// get data from DOM objects, val, texts, whatever
$.post ( "c.php", {
param1: param1,
stuff1: [data from DOM objects...]
},function(data){
console.log(data)
// do something (change dom objects properties, append..)
}
});
</script>
The thing is that all these funtions work well... But they are asyncronous, of course. And I need to:
Execute in order, as if they were syncronous
Besides of it, (and this is one of my challenges) function a receives a param1, but after being executed code will change param1 to another value which will be used to function b.
And, whats more, this happens if trigerred certain DOM event (afterAction Owl Carrousel). If trigerred a different DOM event (selectmenu select), function a will be executed, param1 will keep its value, and function b will be called.
Things that I've tried and didn't worked:
Use $.ajax request (post method and type="text");
var posting = $.post () and posting.done ();
Nest functions in a $.when().then(),
$.when(a()).then(function(){
...
...
$.when(b()).then ({ .... });
});
AjaxQ plugin ($.postq) . But it seems to be very slow, and I dont' know why, it doesn't retrieve data.
What the calls do?
function a inserts data , updates it or deletes it using php and mysqli . It works fine for sure.
function b retrieves data from the same table.
function c retrieves a list of dates and changes the before selectmenu html.
Thanks a lot if you can help me...
ADDED 17/03/2015
A partial solution? Working on it! Change $.post by $.ajax ({... type: 'POST' }) and retrieve data using "return $.ajax" and success callback. Later I need a $.when(a(param1,param2), b(param1*), c(param1)).done(function(data1,data2,data3)){ ... }); statement which I can deal with separate data set. The thing is, when param1 is a different value for a and b functions, to be calculated previously,

Answer 1

A quick way is to chain them is to call each one of them in the callback function of the one you want to be executed previous to that.
For example, since a is your first function, call it, then in its callback manipulate the variables as you need and call b, and do the same in it to call c.
A rough example based on your code:
$(document).ready(function() {
//call function a first
a(param1,param2);
});
function a (param1,param2) {
// get data from DOM objects, val, texts, whatever
$.post ( "a.php", {
param1: param1,
param2: param2,
stuff1: [data from DOM objects...]
},function(data){
console.log(data)
// do something (change dom objects properties, append..)
//change the state of param1 to whatever is required and then call function b
b(param1);
}
});
function b (param1) {
// get data from DOM objects, val, texts, whatever
$.post ( "b.php", {
param1: param1,
stuff1: [data from DOM objects...]
},function(data){
console.log(data)
// do something (change dom objects properties, append..)
//change the state of param1 to whatever is required and then call function c
c(param1);
}
});
function c (param1) {
// get data from DOM objects, val, texts, whatever
$.post ( "c.php", {
param1: param1,
stuff1: [data from DOM objects...]
},function(data){
console.log(data)
// do something (change dom objects properties, append..)
}
});