Javascript Array Passed to PHP Through Ajax - php

Question

I am trying to pass values from a multiple select listbox through Ajax to PHP. I saw some examples in Jquery and JSON, however I am trying to accomplish this just in plain old javascript (Ajax). Here is what I have so far (simplified):
Ajax:
function chooseMultiEmps(str)
{
var mEmpList2 = document.getElementById('mEmpList'); //values from the multi listbox
for (var i = 0; i < mEmpList2.options.length; i++) //loop through the values
var mEmpList = mEmpList2.options[i].value; //create a variable to pass in string
if (window.XMLHttpRequest)
{
xmlhttp = new XMLHttpRequest();
}
else
{
xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp.onreadystatechange = function()
{
if (xmlhttp.readyState == 4 && xmlhttp.status == 200)
{
//specific selection text
document.getElementById('info').innerHTML = xmlhttp.responseText;
}
}
xmlhttp.open("POST", "myPage.php", true);
xmlhttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
var queryString = "&mEmpList=" + mEmpList; //query string should have multiple values
xmlhttp.send(queryString);
}
I can run an alert(mEmpList) and get each value in individual message boxes, however when I retrieve and echo the $_POST['mEmpList'], I get only the first value. Also, when I alert(queryString), I get only one value.
I think I need to create a comma delimited array, and then pass that through the query string. From there, I can use the PHP implode/explode feature to separate the values. Any assistance would be greatly appreciated.

Answer 1

here:
for (var i = 0; i < mEmpList2.options.length; i++) //loop through the values
var mEmpList = mEmpList2.options[i].value; //create a variable to pass in string
you are redefining your mEmpList over and over again, that means only the last value is send
You could do:
var mEmpList = '';
for (var i = 0; i < mEmpList2.options.length; i++) { //loop through the values
mEmpList = mEmpList +','+ mEmpList2.options[i].value; //create a variable to pass in string
}
Also your queryString is not ok, no need for &
var queryString = "mEmpList=" + mEmpList;
That way at the end you will have all values delimite by comma ,
In PHP you can use explode to loop each value:
<?php
$string = explode(',' $_GET['mEmpList']);
for($i=1; $i<count($string); $i++){
echo $string[$i]."<br />";
}
?>