Question

First I have declared a global variable and set it to 0.
In the inner function I want to set the var to another value, but my output won’t set in the (global)outer var, it will be set just as a local var. My other problem is the order in which I get the output.

Output:
third0
first0
second3

$(document).ready(function() {
    state = 0;
    $('#btnlogin').click(function() {
        $.post("php/redirect.php", {
            Username : $('#qi').attr('value'),
            Password : $('#password').attr('value')
        }, function(data) {
            console.log('first'+state);
            state = 3;
            console.log('second'+state);
        });
        console.log('third'+state);
    });
});

Answer 1

It happens because console.log('third'+state); is outside $.post (AJAX) call and calls faster than ajax response.

Seems that you misunderstood that AJAX is asynchronous.