ASP.NET, Visual Studio, C# and Javascript

Question

I have a simple ASPX page based of a master page. On the ASPX page, I have two drop downs and a button. When pressing the button, I want to execute some javascript. To do this, I have used the Button's attribute collection (Add("onclick", script)).

My script looks like this:

string script = "return confirm ('You have selected' + document.getelementbyid(DropDownList1).value + document.getelementbyid(DropDownList2).value)");

Button1.Attributes.Add("onclick", script);

The drop down box element names are spot on, but why doesn't the javascript fire? The button's click event (obviously) gets fired when I click the event, but nothing happens.

This is being done in C#. If I use ASPX and write a basic javascript function in the ASPX markup, intellisense doesn't even come up with a value property for documentgetelementbyid. Why? My browser is fully js enabled (Firefox) as I had this working before but when I added the masterpage and based my ASPX page of that, everything went pear shaped.

Why doesn't the above script works?

Thanks

Change your title question to reflect the actual problem, the title is too generic and misleading. — Binoj Antony
– Binoj Antony, Commented Feb 26, 2009 at 16:37

Oscar Cabrero · Accepted Answer · 2009-02-26 16:29:16Z

5

had you try adding the client ID

string script = "javascript:return confirm ('You have selected' + document.getelementbyid('"+DropDownList1.ClientID+"').value + document.getElementByid('"+DropDownList2.ClienID+"').value)");

edited Feb 26, 2009 at 16:29

answered Feb 25, 2009 at 21:40

Oscar Cabrero

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2 Comments

Tim Over a year ago

I think you'll need quotes round the ID as well i.e. string script = "javascript:return confirm ('You have selected' + document.getelementbyid('"+DropDownList1.ClientID+"').value + document.getelementbyid('"+DropDownList2.ClienID+"').value)");

Tim Over a year ago

Also I think element needs a capital E as well as the I in id i.e. getElementById

toddk · Accepted Answer · 2009-02-25 21:40:46Z

2

I'm not entirely sure of your environment but you may want to take a peek at the source that's being generated by your ASP page. Master pages add a prefix to control names "breaking" the getElementById call. Take a look at the following: http://west-wind.com/weblog/posts/4605.aspx to see if that corrects your problem.

answered Feb 25, 2009 at 21:40

toddk

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Comments

MikeW · Accepted Answer · 2009-02-25 21:36:52Z

1

case sensitive: document.getElementById?

answered Feb 25, 2009 at 21:36

MikeW

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Comments

jlew · Accepted Answer · 2009-02-25 21:36:55Z

1

Shouldn't DropDownList1 and DropDownList2 be in quotes?

answered Feb 25, 2009 at 21:36

jlew

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Comments

mbillard · Accepted Answer · 2009-02-25 21:54:34Z

1

When some JavaScript code seems to not work, it's probably because the syntax is invalid.

To prevent that you can:

Validate your current statement (I'm thinking that maybe the ids of the drop-downs should be surrounded by single quotes).
Try with a simple alert first and see if it works -- alert('Hello world'); --

If not, try playing with the OnClientClick property of the button.

edited Feb 25, 2009 at 21:54

answered Feb 25, 2009 at 21:38

mbillard

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Comments

Bill Martin · Accepted Answer · 2009-02-25 21:39:28Z

0

You also should have the "javascript" in your attributes:

string script = "javascript:confirm ('You have selected' + document.getElementById(DropDownList1).value + document.getElementById(DropDownList2).value)");

Button1.Attributes.Add("onclick", script);

answered Feb 25, 2009 at 21:39

Bill Martin

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