Question

I’m trying to wait for the AJAX request to complete. It would be easy if the method xmlhttp.open would support async = false but Ant Galio does not support this option and only asynchronous requests are permitted. The question is how can I wait for the callback to be called.

    var ajaxFinished = false;
    var xmlhttp = new XMLHttpRequest();
    this.debug("-- onreadystatechange is being defined");
    xmlhttp.onreadystatechange = function() {
        if (xmlhttp.readyState == 4) {
            ajaxFinished = true;
                var data = xmlhttp.responseText;
            if (xmlhttp.status == 200) {
                that.debug('downloadSettings: SUCCESS');
                [...]
            } else {
                that.debug('downloadSettings:');
                that.debug('-- Error: ');
                that.debug('-- ResponseText: "'+data+'"')
            }
        }
    }

    while (ajaxFinished == false) {

    }

    this.debug("-- open connection");
    xmlhttp.open("GET", requestUrl, true); /* Ant Galio does not support synchronous  */
    this.debug("-- send");
    xmlhttp.send();                 

I’m looking for some kind of active waiting. I know about another solution but I’m interested in a solution that would not require changing more of the code than is my example above.

Thanks!

Answer 1

You can’t. There is no “active waiting” in JavaScript, there can be only one active execution a time (“single-threaded”).