Calling a Function in Javascript

Question

I have declared a function for showing a dialog box in jQuery

<script type="text/javascript">
function showDialog(str,strtitle)
 {
if(!strtitle) strtitle='Error message';
$('#dialog').dialog('destroy');
$('#dialog').show();
$('#dialog').html(str);
$("#dialog").dialog({
    resizable: false,
    width: 400,
    color: '#BF5E04',
      open: function () {
                    $(this).parents(".ui-dialog:first").find(".ui-dialog
                                titlebar").addClass("ui-state-error");},

    buttons: {"Ok": function() { 
    $(this).dialog("close");    }},

    overlay: { opacity: 0.2, background: "cyan" },title:strtitle});}
   </script>

And I'm calling this function, in another javascript code:

   <script type="text/javascript">
    var myFile = document.getElementById('myfile');
    //binds to onchange event of the input field
    myFile.addEventListener('change', function() {
    //this.files[0].size gets the size of your file.
     var  size = this.files[0].size;
     document.write(showDialog('size','File Size Exceeds')); 
      });
     </script>

When I execute the function, it writes Undefined, Why the dialog box is not showing. The first function is declred in the head, and the second in the body portion.

It's writing defined because the function showDialog isn't returning anything. The document.write() is not necessary, just simply call showDialog(). — Ivan
– Ivan, Commented Apr 4, 2012 at 15:47
have you tried running it through something like firebug? And stepping through, incidentally: on line 13 of your first section - is that line break there in the real code, or did you put it in to make it fit more neatly? — Zack Newsham
– Zack Newsham, Commented Apr 4, 2012 at 15:49
@Ivan is correct, just one addition: you might want to defer the call to showDialog until the page is loaded: $(showDialog); . — user1233508
– user1233508, Commented Apr 4, 2012 at 15:49
@Ivan how can i return a value from it, I am passing values to it, to show. — Hanya Idrees
– Hanya Idrees, Commented Apr 4, 2012 at 15:51
At the end of the function, just write return "Some text";. — Ivan
– Ivan, Commented Apr 4, 2012 at 15:52

Ivan · Accepted Answer · 2012-04-04 15:49:55Z

3

document.write() is writing what is returned by showDialog(). Since that function isn't returning anything, it will write Undefined.

The document.write() is not necessary, just simply call showDialog().

answered Apr 4, 2012 at 15:49

Ivan

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3 Comments

Hanya Idrees Over a year ago

Ok, but after adding the code , and what you said, it is doing nothing.

Ivan Over a year ago

@Hanya Idrees: What do you mean "it is doing nothing." That is saying very little. Is it throwing an error?

Hanya Idrees Over a year ago

yea, dialog box is an jquery plugin i am using. And the same dialog box function works perfect on another page, called through a onclick event.

abelito · Accepted Answer · 2012-04-04 15:48:34Z

0

You are not returning any value in the showDialog() function.

answered Apr 4, 2012 at 15:48

abelito

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Comments

Mark Walters · Accepted Answer · 2012-04-04 15:50:31Z

0

Just get rid of document.write(), nothing is being returned by showDialog(), hence the undefined error.

<script type="text/javascript">  

  var myFile = document.getElementById('myfile');     
  //binds to onchange event of the input field     
  myFile.addEventListener('change', function() {     
  //this.files[0].size gets the size of your file.      
    var  size = this.files[0].size;      
    showDialog('size','File Size Exceeds');        
  });     

</script>

answered Apr 4, 2012 at 15:50

Mark Walters

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