Calling a javascript function, value returns as undefined in the console

Question

So I have a city dropdown which is populated by an onchange, I am trying to get it so that it doesn't require the onchange every time the page reloads, since it is a form.

this is the states dropdown, which works.

<p id=stateDiv><label>State</label></p><p><select name='States' id='States'  onchange='getCity(this.value)'>
            " . $states . "
        </select></p>";

this is the city drop down function call which does not work. I am new to javascript, so I am not sure about how to format a call with php.

if($state==""){   
echo '<p id="citydiv"></p>';
}else{
    echo '<p id="citydiv"><script type="text/javascript">getCity('.$state.');</script></p>';
}

getCity function

function getCity(stateId)
{
  var strURL="findcity.php?state="+stateId;
  var req = getXMLHTTP();
 if (req)
 {
  req.onreadystatechange = function()
  {
    if (req.readyState == 4) // only if "OK"
    {
      if (req.status == 200)
      {
        document.getElementById('citydiv').innerHTML=req.responseText;
       } else {
         alert("There was a problem while using XMLHTTP:\n" + req.statusText);
       }
    }
   }
   req.open("GET", strURL, true);
   req.send(null);
 }
}

Where's your js and what are you on about? How do you populate your drop down? Why do you need the on change? — Liam Sorsby
– Liam Sorsby, Commented Aug 14, 2013 at 21:59

Niet the Dark Absol · Accepted Answer · 2013-08-14 21:56:11Z

2

When you get problems like this, ALWAYS look at the HTML source. In this case you might see:

getCity(GA);

Clearly this is wrong, that should be "GA".

Whenever you dump a PHP variable into JavaScript, always use json_encode.

answered Aug 14, 2013 at 21:56

Niet the Dark Absol

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1 Comment

EJG Over a year ago

echo '<p id="citydiv"><script type="text/javascript">getCity('. json_encode($state).');</script></p>'; This did it, Thank you.

tastybytes · Accepted Answer · 2013-08-14 22:00:20Z

1

Along with what Kolink said, what does your javascript function "getCity" look like? If it is just returning a value, this will not work. You will either need to grab the element (document.getElementById('cityDiv')) and set the innerHTML to the return value OR use document.write instead of returning a value.

answered Aug 14, 2013 at 22:00

tastybytes

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1 Comment

EJG Over a year ago

I just included it, I have it set this way.

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