Author: Dee Dubs

Change an elements class with JavaScript

To change all classes for an element:

To replace all existing classes with one or more new classes, set the className attribute:

document.getElementById("MyElement").className = "MyClass";

(You can use a space-delimited list to apply multiple classes.)

To add an additional class to an element:

To add a class to an element, without removing/affecting existing values, append a space and the new classname, like so:

document.getElementById("MyElement").className += " MyClass";

To remove a class from an element:

To remove a single class to an element, without affecting other potential classes, a simple regex replace is required:

document.getElementById("MyElement").className =
   document.getElementById("MyElement").className.replace
      ( /(?:^|\s)MyClass(?!\S)/g , '' )
/* code wrapped for readability - above is all one statement */

An explanation of this regex is as follows:

(?:^|\s) # match the start of the string, or any single whitespace character

MyClass  # the literal text for the classname to remove

(?!\S)   # negative lookahead to verify the above is the whole classname
         # ensures there is no non-space character following
         # (i.e. must be end of string or a space)

The g flag tells the replace to repeat as required, in case the class name has been added multiple times.

To check if a class is already applied to an element:

The same regex used above for removing a class can also be used as a check as to whether a particular class exists:

if ( document.getElementById("MyElement").className.match(/(?:^|\s)MyClass(?!\S)/) )

Loop through form post vars in C#

It’s helpful to be able to loop through the form object collection so you know what vars are being posted.
Here is an example from the MSDN docs.

This will display the form vars in a label object…
System.Text.StringBuilder displayValues =
new System.Text.StringBuilder();
System.Collections.Specialized.NameValueCollection
postedValues = Request.Form;
String nextKey;
for(int i = 0; i < postedValues.AllKeys.Length; i++)
{
nextKey = postedValues.AllKeys[i];
if(nextKey.Substring(0, 2) != “__”)
{
displayValues.Append(”
“);
displayValues.Append(nextKey);
displayValues.Append(” = “);
displayValues.Append(postedValues[i]);
}
}
Label1.Text = displayValues.ToString();