Focus in Textbox when the page is Loaded through Ajax

[me2tech]

Hi,

This is ram.

I am developing a page(usereg.jsp ) with two textboxes one for username and another for email. Since i am using this page in main.jsp using Ajax, I am removing the body part in usereg.jsp.

Now i need to focus the cursor in first textbox of usereg.jsp. Since there is no body tag in this jsp i cannot call onload="documen t.formname.text boxname.focus() ".

But i need the focus in textbox when i call this page in main.jsp.

Even i have tried to focus the texbox in usereg.jsp by writing the seperate java script in this page. When i execute just this page(usereg.jsp ) the problem of focusing text box is solved,,

But when i call this page in main.jsp along with the java script i wrote, the focus is not reflecting.

Please suggest me where am i going wrong..

my mailid is: ****

[webhead]

We've all been there. With time, all things pass :)

Yes, but now and then you need a little Ex-Lax to get things moving ;-)

Alrightey. Buckle down and forget everything you learned about JavaScript. Here we go....

function myFunc(x) { return x * 5; }
//  Which is the same as:
//  myFunc = new Function('x', 'return x * 5;');
 
alert(myFunc);
 

What happens here, keeping in mind that myFunc is a variable that stores a Function object?

So anything "new" creates a variable that holds a string, number, or function, right? So if I pass an empty function { } it's just like passing an empty string.

...

initAjax(url, new Function('response', ''));
 

You're actually creating a new anonymous function which takes one argument (response, which will store the returned object from your XMLHttpRequest call automatically [and you don't have to worry about it; just assume that it will]).

A little fuzzy on how that works but right now I'm happy to take your word for it.

Question: We used to do

http.onreadystatechange = http.responseText;;
 

instead of

http.onreadystatechange = callback;
 

. When do we do http.responseTe xt now?

Still no page load, so I started the old put alerts everywhere thing, and it seems to go through all the right motions, yet nothing is put out. I tried it also on a much simpler part of my app, a section in another frame that just puts out a "rate card" of values used in calculations for an invoice. It displays the numbers and takes any changes, only this and nothing more.

Yet no output. But it's small so I'll try and post the whole thing here:

theOutput = 'output'; 
function handleHttpResponse() {
    if (http.readyState == 4) {
        document.getElementById(theOutput).innerHTML = http.responseText;
        }
    }
 
function getHTTPObject() {
    var xmlhttp;
    /*@cc_on
    @if (@_jscript_version >= 5)
        try { xmlhttp = new ActiveXObject("Msxml2.XMLHTTP"); } 
        catch (e) {
            try { xmlhttp = new ActiveXObject("Microsoft.XMLHTTP"); } 
            catch (E) { xmlhttp = false; }
            }
    @else
        xmlhttp = false;
        @end @*/
        if (!xmlhttp && typeof XMLHttpRequest != 'undefined') {
            try { xmlhttp = new XMLHttpRequest(); } 
            catch (e) { xmlhttp = false; }
            }
        return xmlhttp;
    }
 
function initAjax(url, callback) {
    var http = getHTTPObject(); 
    http.open("GET", url, true);
    http.onreadystatechange = callback;
    http.send(null);
    }
/////////////////////////////////////////////////////////////////////////////////
function getRatecard() {
    url = "Rfunc.php";
    initAjax(url, function response(){ });
    }    
 
function rChange(theField) {
    fldnam=document.getElementById(theField).name;
    fldval=document.getElementById(theField).value;
    url = 'Rfunc.php?fldn='+fldnam+'&fldv='+fldval; 
    initAjax(url, function response(){ });
    } 
 
function rReport() {
    url = 'Rfunc.php?report=recvbls'; 
    initAjax(url, function response(){ });
    } 

[webhead]

Interesting:

function getRatecard() {
    url = "Rfunc.php";
    initAjax(url, function response(){ document.getElementById(theOutput).innerHTML = http.responseText; }); 
    }    

puts out nothing but:

function getRatecard() {
    url = "Rfunc.php";
    initAjax(url, function response(){ document.getElementById(theOutput).innerHTML = 'blah'; }); 
    }    

puts out "blah". Looks like we just aren't putting anything into ...innerHTML, because by the time we get to that statement the responseText is gone.

[pbmods]

Go back and reread my last post.

[pbmods]

So anything "new" creates a variable that holds a string, number, or function, right? So if I pass an empty function { } it's just like passing an empty string.

Basically, considering that when you pass an empty string, you're actually passing an instance of the String class without a value:

doSomething('') === doSomething(new String(''));
doSomething(function() {}) === doSomething(new Function('', ''));
 

Question: We used to do

http.onreadystatechange = http.responseText;;
 

instead of

http.onreadystatechange = callback;
 

. When do we do http.responseTe xt now?

This is where that 'response' that you keep confusing for the function's name comes into play.

NOTE WHERE I PUT 'RESPONSE'. IT GOES INSIDE THE PARENTHESIS.

initAjax(url, function (response) { eval(response.responseText); });
 
initAjax(url, new Function('response', 'eval(response.responseText);'));
 

The two statements do exactly the same thing. Remember that when http.onreadysta techange fires, it will automatically pass the result as the first parameter.

Fix your callbacks, and things should start working.

[webhead]

Oops, how did I do that with the ()? Fixed, added the eval, but still nothing. Tried this too and still nothing:

function initAjax(url, callback) {
    var http = getHTTPObject(); 
    http.open("GET", url, true); 
    http.onreadystatechange = callback;
    http.send(null);
    }
 
function getRatecard() {
    url = "Rfunc.php";
    initAjax(url, function (response) { 
        eval(response.responseText); 
        document.getElementById(theOutput).innerHTML = response.responseText;
        }); 
    }    

Sorry I'm not catching on too well, maybe I need to go back and find some more beginner tutorials. But you've been a most patient teacher and I am very grateful for your help.

[pbmods]

Oops, how did I do that with the ()? Fixed, added the eval, but still nothing. Tried this too and still nothing:

function initAjax(url, callback) {
    var http = getHTTPObject(); 
    http.open("GET", url, true); 
    http.onreadystatechange = callback;
    http.send(null);
    }
 
function getRatecard() {
    url = "Rfunc.php";
    initAjax(url, function (response) { 
        eval(response.responseText); 
        document.getElementById(theOutput).innerHTML = response.responseText;
        }); 
    }    

Ok, this is looking pretty good. But now we have a conflict:

        eval(response.responseText); 
        document.getElementById(theOutput).innerHTML = response.responseText;
 

I used the 'eval' line just as an example, because I wasn't sure what you were getting back from your server-side script. But it looks like the script is sending HTML, not JavaScript. So you can go ahead and remove the 'eval' line (since eval(html code) will produce an error):

function getRatecard() {
    url = "Rfunc.php";
    initAjax(url, function (response) { 
        document.getElementById(theOutput).innerHTML = response.responseText;
        }); 
    }

Sorry I'm not catching on too well, maybe I need to go back and find some more beginner tutorials. But you've been a most patient teacher and I am very grateful for your help.

I'm having fun, I promise. I know we all make typos occasionally (I happen to hold the world record for typos per hour, and I broke it three times last weeek^K^Kk). I apologize for my outburst.

[webhead]

function getRatecard() {
    url = "Rfunc.php";
    initAjax(url, function (response) { 
        document.getElementById(theOutput).innerHTML = response.responseText;
        }); 
    }

Done, but still nothing from "response.respo nseText;". Is it possible we need to wait for "http.readyStat e == 4"? I tried putting that around the "...innerHTML.. ." line but still nothing.

I'm having fun, I promise. I know we all make typos occasionally (I happen to hold the world record for typos per hour, and I broke it three times last weeek^K^Kk). I apologize for my outburst.

No prob. I know I can get on people's nerves with endless questions, especially when it's free edjamakashun. Thanks again.

[pbmods]

Done, but still nothing from "response.respo nseText;". Is it possible we need to wait for "http.readyStat e == 4"?

Ooh. Good point. Alrightey. Let's add another layer of complexity to initAjax:

function initAjax(url, callback) {
    var http = getHTTPObject(); 
    http.open("GET", url, true); 
    http.onreadystatechange = function(response) {
        if(response.readyState == 4)
            callback(response);
    };
    http.send(null);
    }
 

We create a new anonymous function that checks for response's readyState (remember that response is set to the result from the AJAX call automatically when you assign it to http.onreadysta techange; http is undefined outside of initAjax, so we pass the response through callbacks). If it is 4, then we call callback and pass the response to it. Otherwise, we do nothing.

I tried putting that around the "...innerHTML.. ." line but still nothing.

Hm.

Try alerting your responseText to see if your script is sending anything back to you.

initAjax(url, function (response) { 
        alert(response.responseText);
        }); 
 

[webhead]

Try alerting your responseText to see if your script is sending anything back to you.

initAjax(url, function (response) { 
        alert(response.responseText);
        }); 
 

Tried this:

function initAjax(url, callback) {
    var http = getHTTPObject(); 
    http.open("GET", url, true);
    http.onreadystatechange = function(response) {
        if (response.readyState == 4) { callback(response); } 
        };
    alert('ack');
    http.send(null);
    }
 
function getTestpage() { 
    url = "afunc.php";
    initAjax(url, function (response) { 
            document.getElementById(theOutput).innerHTML = response.responseText;
            alert(response.responseText);
        });
    alert('done');
    }    

I get alerts for "ack" and "done" but not "response.respo nseText". Not even a blank alert, no alert at all.

[pbmods]

Tried this:

function initAjax(url, callback) {
    var http = getHTTPObject(); 
    http.open("GET", url, true);
    http.onreadystatechange = function(response) {
        if (response.readyState == 4) { callback(response); } 
        };
    alert('ack');
    http.send(null);
    }
 
function getTestpage() { 
    url = "afunc.php";
    initAjax(url, function (response) { 
            document.getElementById(theOutput).innerHTML = response.responseText;
            alert(response.responseText);
        });
    alert('done');
    }    

I get alerts for "ack" and "done" but not "response.respo nseText". Not even a blank alert, no alert at all.

Here's why you're not seeing anything:

heh

Because http actually *isn't* automatically assigning a value to response. I went back and looked at my AJAX frameworks, and it turns out that you have to manually do this.

Yeah. *sheepish grin*

So anyway, here's what initAjax *really* should look like (are we having fun yet?):

function initAjax(url, callback) {
    var http = getHTTPObject(); 
    http.open("GET", url, true);
    http.onreadystatechange = function() {
        if (http.readyState == 4) { callback(http); } 
        };
    http.send(null);
    }