How to have a function with event object and parameter

Question

I show a page in a jQuery dialog box. The user fills in the fields and submits the form.

In the function I need to call e.preventDefault(). In the underlying code I used the RegisterStartupScript method on the submit button. I know how to do it by passing parameters:

System.Web.UI.ScriptManager.RegisterClientScriptBlock(Page, GetType(Page),
 "Script", "OrderForm('Item.aspx?OrderNum=" & _ID & "');", True)

How can I pass an event object in registerStartupScript?

I want a function like this:

function OrderForm(e, number) {
 e.preventDefault();
 //do something using number;
}

• Barmar: Where does the number come from when you click on the button?
• Barmar: There's no such thing as <btn>. Did you mean for that to be a class or ID?
• kosmos: As I understand, when you call to OrderForm() from RegisterClientScriptBlock(), there is no event to pass because you are calling the method directly. I mean in your code there is no event to handle. See the example from msdn; in that example is possible to pass an event because the user needs to click the button.

Answer 1

The .click() method is part of a framework (in this case I'm pretty sure it's jQuery) and it accepts a predefined number of arguments. You can use (for example) a data- attribute in your button with the number and then access to it through the object this.

// html
<button data-number="3">my button</button>
// js
$('button').click(function(e){
 e.preventDefault();
 var number = $(this).data().number; // or $(this).data('number')
 alert(number);
});

Try with this jsfiddle: https://jsfiddle.net/q3fvxk93/

• Barmar: It should be $(this).data("number")
• kosmos: .data() returns an object. It is accessible (also) by object notation.
• Barmar: True, although the usual way to call it is with the data name argument. Returning the entire data object is mainly useful if you need very efficient access to multiple properties.
• kosmos: Well, .data().something returns just the value for something. Is it less efficient than .data('something')? Sincerely I don't know (I will review it in free time), but probably is the same (talking about performance).
• Barmar: Unless you're accessing multiple data values, the performance difference is probably negligible. .data().something returns the whole data object, then performs an object property access to get the value for just something.

Answer 2

the event object is in the scope $(this) I don't know where number should come from.

So your code would look this

$('btn').click(function(e) {
 e.preventDefault();
 $(this).attr('id'); //the button and it's properties like attributes in this example I get the ID of the button
});