Question

I have global variable fan_coil_ai_bi, and I use that variable to store some data which I get from request, but problem is that len_1 is 1 ( what is ok value in this case ) and len_2 is undefined (what is wrong). How that happen in my function bellow ? How to achieve that len_2 have same value like len_1 ? What is wrong with this code ?

function read_required_fields(fan_coil_id) {
    var parameters = {};

    parameters['command'] = 'read_required_fields';
    parameters['fan_coil_id'] = fan_coil_id;

    $.get("php_scripts/network_script.php", parameters, function(data) {
        fan_coil_ai_bi=data;
        alert('len_1='+fan_coil_ai_bi.length);
    }, "json");
    alert('len_2='+fan_coil_ai_bi.length);
}

Answer 1

Asynchronous JavaScript and XML is asynchronous.

The get method means “Make an HTTP get request and when it gets a response, do this”.

It does not pause execution of the function until the HTTP response arrives.

If you want to do anything with the data, do it in the callback function (or a function you call from it).

$.get("php_scripts/network_script.php", parameters, function(data) {
    fan_coil_ai_bi=data;
    alert('len_1='+fan_coil_ai_bi.length);
    alert('len_2='+fan_coil_ai_bi.length);
}, "json");