Get data from API call in JavaScript

Question

I am new to JS and I want to open a new window when I click on my button in SugarCRM without browser blocking it.

function authenticateCalendar() {
    var result;
    var url = app.api.buildURL("Users", 'authenticate_calendar');
    app.api.call('retrieve', url, null, {
        success: function(data) {
            if(data.needAuth) {
                result = JSON.parse(data.url) ;
            }
            else result = false;
        }
    });
    if(result)
        window.open(result);
}
<input type="button" onclick="authenticateCalendar();">

Is it possible to get the data.url string in my function?