Send javascript function parameters onChange

Question

Okay, I've been struggling with this for a few hours now. I'm using ajax to update a div in my site with a php code however, i'm trying to send parameters in the function from the external javascript file to update the correct link(there are multiple drop down boxes)

for example: this is my select box

<script type='text/javascript' src='ajax.js'></script>//include ajax file
<select onchange='MakeRequest(raceupdate);
        this.options[this.selectedIndex].value;'> //so no use of a button is needed to auto link to anchor tag
        <option>Deathmateched</option>
    <?php
        dmList()
        ?>

 </select>

Then next my external ajax function MakeRequest().

function MakeRequest(value)
{
    var linkInfo = "teleport.php?call=" + value;//create appropriate link depending on function parameters  
    var xmlHttp = getXMLHttp();

    xmlHttp.onreadystatechange = function()
    {
        if(xmlHttp.readyState == 4)
        {
            HandleResponse(xmlHttp.responseText);
        }
    }     

    xmlHttp.open("GET", linkInfo, true); //update page using link info variable created above
    xmlHttp.send(null);

}

So as you can see I'm trying to pass a sting of text into this function, but I seem to be failing somewhere.

the 'value' variable is been passed as undefined if I put it in an alert box — user1426658
– user1426658, Commented May 31, 2012 at 1:00
Are you trying to pass the string "raceupdate" to MakeRequest or is there a variable somewhere called raceupdate? — Musa
– Musa, Commented May 31, 2012 at 1:02

Techgration · Accepted Answer · 2012-05-31 01:07:20Z

1

You probably want to setup your tag to pass "this". I don't see where your raceupdate variable is declared, unless it's global... in which case you should show us what you're doing with that variable.

<select onchange='MakeRequest(this);'> 
    <option>Deathmateched</option>
    <?php
        dmList();
    ?>

If you did it that way, you'd have to change this function as such:

    function MakeRequest(element)
    {
    var linkInfo = "teleport.php?call=" + element.value;//create appropriate link depending on function parameters  
    var xmlHttp = getXMLHttp();

    xmlHttp.onreadystatechange = function()
    {
        if(xmlHttp.readyState == 4)
        {
            HandleResponse(xmlHttp.responseText);
        }
    }     

    xmlHttp.open("GET", linkInfo, true); //update page using link info variable created above
    xmlHttp.send(null);

}

And what are you trying to do here?

this.options[this.selectedIndex].value;

In your comments, it looks like you're saying you want to jump to an anchor tag? If so, then you would want to do something like

var anchorTag = document.getElementID("YOUR_ANCHOR_TAG_ID");
anchorTag.focus();

answered May 31, 2012 at 1:07

Techgration

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1 Comment

user1426658 Over a year ago

Thanks, Make the changes you suggested and everything works fine!

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