Ajax不显示输出

I Wrote a simple code using php that fills in rows and columns with an *. Ive tested the php conde by typing the url localhost/squareService.php?rows=3&cols=3

but when I have a user try to enter the number of rows and columns using js and html nothing happens. I can't seem to find where this code fails.

note:the php is in a seperate file called squareService.

 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

    <html lang="en">
    <head>
        <title>consume Square Service</title>
        <script language ="javascript" type="text/javascript">

        var xmlhttp;

        function drawSquare(){

            xmlhttp = new XMLHttpRequest();
            var rows= document.GetElementById("rows").value;
            var cols= document.getElementById("cols").value;
            var url ="squareService.php?rows=" + rows + "&cols=" + cols;
            console.log(url);

            }



        </script>

    </head>
    <body>
        <div id="results"></div>
        Rows:<input type="text" id="rows"/> <br/>
        Columns:<input type="text" id="cols"/> <br/>
        <input type ="button" value="Draw Square" onclick="drawSquare()"/>

    </body>
    </html>

<?php
    $rows = $_REQUEST['rows'];
    $cols= $_REQUEST['cols'];

        for($i=0; $i<$cols; $i++)
        {
            for($x=0; $x<$rows; $x++)
            {
                print("*");
            }
            print("<br/>");
        }



    ?>

Simple typo,

Change

var rows= document.GetElementById("rows").value;

to

var rows= document.getElementById("rows").value;

Remember, JavaScript is case-sensitive.

Reference

never mind! as soon as posted it after an hour of staring I realized that I had a typo original was "GetElementById" It should have been "getElementById"

Correct this section of your code :

function drawSquare(){

            xmlhttp = new XMLHttpRequest();
            var rows= document.getElementById("rows").value;
            var cols= document.getElementById("cols").value;
            var url ="squareService.php?rows=" + rows + "&cols=" + cols;
            console.log(url);

            }

Always remember JS is case-sensitive. so GetElementById is different from getElementById