Calling the following javascript for a user control.

[mike55]

Hi all,

 

I have the following javascript that prevent someone typing more that 145 characters in a text box.

 

However the problem is that it is for a web page, and needs variables such as the form name etc. How can I implement it on a user control. Am using a string variable and enclosing each line of javascript with the following:

script &= " [i]Javascript code[/i]  " & vbCrLf

 

I then user the following code to register the entire javascript:

      If Not Page.IsStartupScriptRegistered(scriptName) Then
           ' Register the script.
           Page.RegisterStartupScript(scriptName, script)
       End If
   End Sub

 

Here is the javascript that I was using:

var MaximumCharacters = "145";
		var MaximumWords = "0";
		var FormName = "Form1";
		var TextFieldName = "txtMessage";
		var CharactersTypedFieldName = "";
		var CharactersLeftFieldName = "CharsLeft";
		var WordsTypedFieldName = "";
		var WordsLeftFieldName = "";


		var WordsMonitor = 0;
		var MaxWords = parseInt(MaximumWords);
		var MaxChars = parseInt(MaximumCharacters);
		var textfield = 'document.' + FormName + '.' + TextFieldName + '.value';

		function WordLengthCheck(s,l) { 
		WordsMonitor = 0;
		var f = false;
		var ts = new String();
		for(var vi = 0; vi < s.length; vi++) {
			vs = s.substr(vi,1);
			if((vs >= 'A' && vs <= 'Z') || (vs >= 'a' && vs <= 'z') || (vs >= '0' && vs <= '9')) { 
				if(f == false)	{
					f = true;
					WordsMonitor++;
					if((l > 0) && (WordsMonitor > l)) {
						s = s.substring(0,ts.length);
						vi = s.length;
						WordsMonitor--;
						}
					}
				}
			else { f = false; }
			ts += vs;
			}
		return s;
		} // function WordLengthCheck()

		function CharLengthCheck(s,l) { 
		if(s.length > l) { s = s.substring(0,l); }
		return s;
		} // function CharLengthCheck()

		function InputCharacterLengthCheck() {
		if(MaxChars <= 0) { return; }
		var currentstring = new String();
		eval('currentstring = ' + textfield);
		var currentlength = currentstring.length;
		eval('currentstring = CharLengthCheck(' + textfield + ',' + MaxChars + ')');
		if(CharactersLeftFieldName.length > 0) {
			var left = 0;
			eval('left = ' + MaxChars + ' - ' + textfield + '.length');
			if(left < 0) { left = 0; }
			eval('document.' + FormName + '.' + CharactersLeftFieldName + '.value = ' + left);
			if(currentstring.length < currentlength) { eval(textfield + ' = currentstring.substring(0)'); }
			}
		if(CharactersTypedFieldName.length > 0) {
			eval('document.' + FormName + '.' + CharactersTypedFieldName + '.value = ' + textfield + '.length');
			if(currentstring.length < currentlength) { eval(textfield + ' = currentstring.substring(0)'); }
			}
		} // function InputCharacterLengthCheck()

		function InputWordLengthCheck() {
		if(MaxWords <= 0) { return; }
		var currentstring = new String();
		eval('currentstring = ' + textfield);
		var currentlength = currentstring.length;
		eval('currentstring = WordLengthCheck(' + textfield + ',' + MaxWords + ')');
		if (WordsLeftFieldName.length > 0) {
			var left = MaxWords - WordsMonitor;
			if(left < 0) { left = 0; }
			eval('document.' + FormName + '.' + WordsLeftFieldName + '.value = ' + left);
			if(currentstring.length < currentlength) { eval(textfield + ' = currentstring.substring(0)'); }
			}
		if (WordsTypedFieldName.length > 0) {
			eval('document.' + FormName + '.' + WordsTypedFieldName + '.value = ' + WordsMonitor);
			if(currentstring.length < currentlength) { eval(textfield + ' = currentstring.substring(0)'); }
			}
		} // function InputWordLengthCheck()

		function InputLengthCheck() {
		InputCharacterLengthCheck();
		InputWordLengthCheck();
		} // function InputLengthCheck()

		//-->

 

Any suggestions would be appreciated.

 

Mike55.

[Nate Bross]

Why not use the property of the input box?

<input type="text" value="" maxlength="145">

[Diesel]

Lol.

 

All that trouble.

[Nate Bross]

Let me know if that works, I may have misunderstood your problem, and over simplifyed the answer.

[Nate Bross]

By the way, congrats Diesel on 500 posts even, at least at 10:23 (-7:00)December 15th ;)

 

Didn't you also used to live in Lombard IL?

[Diesel]

Yessir. Been in San Diego about a month now. Fun place.

[mike55]

The problem with setting the value in the code behind is that I am using a multi-line textbox, and I also I need to display the number of characters the user has left. Displaying the number of characters is optional.

 

Mike55.

[Nate Bross]

What is the exact error you are getting?

[HJB417]

I would think that setting the value in code behind would cause the the creation of the maxlength attribute by the asp.net runtime. DOM had access to the attributes of elements.

[Diesel]

HJ, what would that matter if the browser has no idea what to do with the attribute...anyway, do a search for textarea maxlength, there's a lot of javascript functions that will accomplish what Mike wants to do. I put a link up in his re-post of this topic.

[HJB417]

The browser knows what to do with the maxlength attribute. It's a simple (not the best) way of preventing buffer overflow.

 

http://www.smartwebby.com/DHTML/textbox_characters_counter.asp

 

Also, since the asp.net runtime will emit an autogenerated name for the control. It can be accessed before Render using Control.ClientID

[Diesel]

Dude, the link you posted has nothing to do with the browser. It's a javascript function that uses the maxlength attribute. It's a good idea though...instead of passing the value everytime you call the function.

[HJB417]

ya, exactly. Maybe saying 'browser' wasn't the best way to say what I meant.

I hinted javascript when I said 'DOM had access to the attributes of elements.'

 

I know his code will require a bit more trickery since the id of the control is being created by the runtime. I think what I've done in the past was create a global javascript variable that was either a struct/class or a hashtable that was able to get the clientId/true id of a control.

[Diesel]

No, that code should work as is for his control.

When you call the javascript function from the control, the control is passed in as an object through the event var, so no id is needed.

[HJB417]

No, that code should work as is for his control.

When you call the javascript function from the control, the control is passed in as an object through the event var, so no id is needed.

 

sweet, i didn't know that.