returning xmlhttp responseText from function as return

Question

im new in javascript and php , my goal is :RETURN string from xmlhttp responseText to a function return value.So i can use it with innerText or innerHTML method. the html code :

<script>
function loadXMLDoc(myurl){
    var xmlhttp;
    if (window.XMLHttpRequest){
        xmlhttp=new XMLHttpRequest();}
    else{
        xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");}

     xmlhttp.onreadystatechange=function(){
         if (xmlhttp.readyState==4 && xmlhttp.status==200){
              xmlhttp.responseText;}
     }

    xmlhttp.open("GET",myurl,true);
    xmlhttp.send();
}
</script>

Answer 1

You can't.

Neither runs the code syncronous, nor would you return anything to loadXMLDoc but to the anonymous function which is the onreadystatechange handler.

Your best shot is to pass a callback function.

function loadXMLDoc(myurl, cb) 
{
   // Fallback to Microsoft.XMLHTTP if XMLHttpRequest does not exist.
   var xhr = (window.XMLHttpRequest ? new XMLHttpRequest() : new ActiveXObject("Microsoft.XMLHTTP"));

    xhr.onreadystatechange = function()
    {
        if (xhr.readyState == 4 && xhr.status == 200)
        {
            if (typeof cb === 'function') cb(xhr.responseText);
        }
    }

   xhr.open("GET", myurl, true);
   xhr.send();

}

And then call it like

loadXMLDoc('/foobar.php', function(responseText) {
    // do something with the responseText here
});