在页面加载时也触发onchange html事件

Question

Ok I have a onchange event on a select field. It now works great. When the dropdown "networks" is changed it refreshes the second dropdown. I also want the ajax code at the top to trigger on page load as well as onchange so the second list gets populated. This is due to it being on an edit page. Here is the ajax call im using first

function get_cities(networks) {
    $.ajax({
        type: "POST",
        url: "select.php", /* The country id will be sent to this file */
        beforeSend:     function () {
            $("#folder").html("<option>Loading ...</option>");
        },
        //data: "idnetworks="+networks,
        data: "idnetworks="+networks +"&doc="+ <?php echo $row_rs_doc['parentid']; ?>,
        success: function(msg){
            $("#folder").html(msg);
        }
    });
} 

now the two dropdown boxes

<label for="networks"></label>
<select name="networks" id="networks" onChange='get_cities($(this).val())'>
    <?php
    do {  
    ?>
        <option value="<?php echo $row_rs_net['idnetworks']?>"<?php if (!(strcmp($row_rs_net['idnetworks'], $row_rs_doc['network']))) {echo "selected=\"selected\"";} ?>><?php echo $row_rs_net['netname']?></option>
    <?php
    } while ($row_rs_net = mysql_fetch_assoc($rs_net));
    $rows = mysql_num_rows($rs_net);
    if($rows > 0) {
        mysql_data_seek($rs_net, 0);
        $row_rs_net = mysql_fetch_assoc($rs_net);
    };
    ?>
</select>
<select name="folder" id="folder">
</select>

Answer 1

You can use .trigger() to trigger a change event onto the select-box so the onchange code will be called like it would if the user just switched the option.

jQuery('#networks').trigger('change');

Just include this into the load event/function for the page.

jQuery(document).ready(function() {
    jQuery('#networks').trigger('change');
});

Answer 2

I'm not 100% clear what you want but the standard way to do something with JQuery when the page is loaded, is to use

$(document).ready(handler)

This waits till the page is "ready" which is better.

So, in your document head you'd have something like this...

<script type="text/javascript">
$(document).ready( function(){
  do_some_stuff();
});
</script>

Answer 3

Can't you just call get_cities($('#networks').val()) when the DOM is ready?

$(function() { // will be run by jQuery when DOM is ready
  get_cities($('#networks').val());
});