用Ajax调用PHP程序

I have a PHP program for counting user banner clicks. My banner link is something like this:

<a href="<?=$banner_url;?>" onclick="banner_click_count('<?=$banner_id;?>')"><img src=...>

When user clicks on image, it runs banner_click_count() function with $banner_id as parameter.

function banner_click_count($ban_id)
{
$.ajax({
   type: "POST",
   url: 'banner_click.php',
   data: {banner_id: $ban_id}
   });

}

At banner_click.php, I get the banner_id with $banner_id = $_GET['banner_id']);, search the database based on it. Find the record, then add 1 to banner_count column field. After that, redirect to banner_url.

When I run the program, I get Parse error: parse error, expecting T_VARIABLE' or '$'' on line $.ajax({

Addendum: the error is cleared with all your help, but when I click on the link it redirects to banner_url directly and does not run the AJAX function.

Addendum:I put the alert("hello"); at the top of ajax function and i got it. So it goes into function

1.You need to put your javascript function under <script> tag

2.you need to pass json string as post data

3.though you are passing your data as post so you will get this data in php as $_POST not $_GET

So change your function as below

<script>
function banner_click_count(ban_id)
{
$.ajax({
   type: "POST",
   url: 'banner_click.php',
   data: {banner_id: ban_id}
   });

}
</script>

// in your php use as below
echo $_POST['banner_id']

Make sure banner_id is in quotes and that you are including JQuery in your page. And don't forget a success/error return.

$.ajax({
   type: "POST",
   url: 'banner_click.php',
   data: {'banner_id': $ban_id},
   success: function(s) { 
     console.log('success' + s);
   },
   error: function(e) {
     console.log('error' + e);
   }
});

Don't we need a return false before the function ends?

I found the solution. Thanks to all.

function banner_click_count(ban_id)
{
  $.post(
  "banner_click.php",
  {
  banner_id: ban_id
  });
}