Why does javascript sometimes output undefined variable

Question

I have a small button which when pressed asks for a name and then adds the input to the URL which can then be processed by PHP. My code is below.

    function staff_prompt(url)
  {
  var url = url;
  var staffname=prompt("Please enter your Name below:","Staff Member Name");
  if (staffname == null)  {
  } 
  else if (staffname == "Staff Member Name") {
  alert('You must enter a value to continue');
  staff_prompt();
  }
  else if (staffname == "") {
  alert('You must enter a value to continue');
  staff_prompt();
  }
  else {
  var windowgo = url + "&staffmember=" + staffname;
  window.location = windowgo;
 }
 }

My Button code is below

onclick="staff_prompt('index.php?app=orders&page=action&action=go_orderedviewtype=<?php echo $viewtype ?>&orderid=<?php echo $orderid ?>')

Sometimes it works well, however other times it seems to go to "http://undefined....ect" I cannot replicate the situation, sometimes it happens and sometimes not

I am thinking that maybe the code is not very good... why would the javascript not detect sometimes the variable 'url'.

use qunit to test your function qunitjs.com

Jonathan de M.
– Jonathan de M.

2012-12-24 08:32:15 +00:00
Commented Dec 24, 2012 at 8:32 — Jonathan de M.
– Jonathan de M., Commented Dec 24, 2012 at 8:32

Rikesh · Accepted Answer · 2012-12-24 08:33:38Z

3

Yes, there is problem in your code.

You are calling staff_prompt() function from both of your else if conditions & you have not passed the url in it as a parameter, so it will definitely take it as undefined.

answered Dec 24, 2012 at 8:33

Rikesh

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1 Comment

user1641165 Over a year ago

Thanks - I guess that's why it only happened sometimes :)

Konstantin Dinev · Accepted Answer · 2012-12-24 08:33:27Z

2

Here URL is undefined. You are calling the function with an undefined parameter:

staff_prompt();

So as long as you get into the else if-s you would be getting the undefined url.

Change your code to staff_prompt(url); and you would be fine.

answered Dec 24, 2012 at 8:33

Konstantin Dinev

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Comments

Burlak Ilia · Accepted Answer · 2012-12-24 08:52:11Z

0

When you call staff_prompt after an error, you do not pass it url.

function staff_prompt(url) {
    var url = url;
    var staffname=prompt("Please enter your Name below:","Staff Member Name");
    if (staffname == null)  {
    } else if (staffname == "Staff Member Name") {
        alert('You must enter a value to continue');
        staff_prompt(url);
    } else if (staffname == "") {
        alert('You must enter a value to continue');
        staff_prompt(url);
    } else {
        var windowgo = url + "&staffmember=" + staffname;
        window.location = windowgo;
    }
}

Example: http://jsfiddle.net/burlak/CsrTc/3/

answered Dec 24, 2012 at 8:52

Burlak Ilia

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