A Global Variable set by a function cannot be used from other Function in Javascript

Question

First, I would like to explain what I really want to do. I have some JS functions with ajax multiple times and also some functions. I want to place all such functions in a single place and make access form everywhere in my project. My first problem is that I cannot pass a ajax:success return into variables. Please guide me. My second problem is I tried some workaround and found that I cannot use a variable set in those functions. Other variables and functions are OK. Please check the codes and help me.

let result_data = null;
function ext_data(php_path, data_string){
    return{
        php_path,
        data_string,
        exec: function(callbaclFunc){
            let responseObject = null;
            $.ajax({
                url: this.php_path,
                type: 'POST',
                dataType: 'JSON',
                data: this.data_string,
                success: function(responseObject){
                    callbaclFunc(responseObject);
                }
            });
        }
    };
}//End of ext_data
function get_obd_data(){
    let data_string = cdc_check();
    if (data_string !== "false"){
        //let responseObject = null;
        let php_path = '../php/insert_update_delete_obd_data.php';
        let obd_data = ext_data(php_path, data_string);
        //obd_data.exec(function(fetch_data){console.log(fetch_data);});
        //result = obd_data.exec(function(fetch_data){return fetch_data;});
        obd_data.exec(fetch_data);
        console.log(result_data);
    }
}//End of get_obd_data()
function fetch_data(responseObject){
    //console.log(responseObject);
    result_data = responseObject;
    console.log(result_data);
}//End of fetch_data

If I check console, I receive result_data as null when I call from get_obd_data. When I check in fetch_data, all works OK. Please see the attached screenshot. Please help me.

console screedshot

It works but you are logging too soon. If you wait until the result finishes then you should see it. Replace `obd_data.exec(fetch_data); console.log(result_data)` with `obd_data.exec(fetch_data); setTimeout(()=>console.log(result_data),2000)` to wait for 2 seconds to prove that the global variable is set — slebetman, Apr 21 '20 at 01:49
The correct way to wait for `result_data` is to execute your code in the callback: `obd_data.exec((response) => {fetch_data(response); console.log(result_data)})`. Basically replace `fetch_data` with your actual code you want to execute — slebetman, Apr 21 '20 at 01:50

A Global Variable set by a function cannot be used from other Function in Javascript

0 Answers0