Need some help with this javascript

M

mike55

Contributor
Joined
Mar 26, 2004
Messages
727
Location
Ireland
Hi,

Got my hands on this piece of javascript:
Code: 
	<!-- Copyright 2004 Bontrager Connection, LLC
			// For additional information about this JavaScript 
			//    and how to use it, see the 
			//    "Displaying Number of Words Typed Into Form Fields" 
			//    article, linked from the archives at 
			//    from [url]http://willmaster.com/possibilities/archives/[/url]
			// The above note and the copyright line must remain with 
			//    this JavaScript source code. Comments below this 
			//    point in the code may be removed if desired.

			//
			// Customizing this JavaScript code requires specifying 
			//    eight values.
			//

			// Value One:
			// Specify the maximum number of characters the form field 
			//    may contain. If you have no maximum, specify 0 (zero).
			var MaximumCharacters = "160";


			// Value Two:
			// Specify the maximum number of words the form field may 
			//    contain. If you have no maximum, specify 0 (zero).

			var MaximumWords = "0";


			// Value Three:
			// Specify the form's name (provided by the name="_____" 
			//    attribute in the FORM tag).

			var FormName = "Form1";


			// Value Four:
			// Specify the name of the text field being monitored 
			//    (provided by the name="_____" attribute in the 
			//    INPUT or TEXTARE tag).

			var TextFieldName = "txtMessage";


			// Value Five:
			// Specify the field name where where is to be displayed 
			//    the number of characters the user has typed. Make 
			//    it blank (nothing between the quotation marks) if 
			//    you aren't displaying the number of characters typed.

			var CharactersTypedFieldName = "";


			// Value Six:
			// Specify the field name where where is to be displayed 
			//    the number of characters left that may be typed. 
			//    Make it blank (nothing between the quotation marks) 
			//    if you aren't displaying the number of characters 
			//    left.

			var CharactersLeftFieldName = "CharsLeft";


			// Value Seven:
			// Specify the field name where where is to be displayed 
			//    the number of words the user has typed. Make it 
			//    blank (nothing between the quotation marks) if you 
			//    aren't displaying the number of words typed.

			var WordsTypedFieldName = "";


			// Value Eight:
			// Specify the field name where where is to be displayed 
			//    the number of words left that may be typed. Make it 
			//    blank (nothing between the quotation marks) if you 
			//    aren't displaying the number of words left.

			var WordsLeftFieldName = "";




			//////////////////////////////////////////////////////
			//                                                  //
			//  No modfications are required below this point.  //
			//                                                  //
			//////////////////////////////////////////////////////

			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()

I set the MaximumCharacters to the maximum number of characters I want to have in a particular field. However I need the value set to be dependent of the value selected from a asp.net dropdown list. My drop down list contains the following values: "Email", "SMS", and "Email & SMS".

If the value selected is "Email" then the MaximumCharacters must be set to 500, otherwise if the values "SMS" or "Email & SMS" is then I need to set the MaximumCharacters to 160.

My question is therefore how do I do an if statement in javascript that does the following:
Code: 
if me.ddMessage.selectedValue = "Email" then
MaximumCharacters = 500
elseif me.ddMessage.selectedValue = "SMS" or me.ddMessage.selectedValue = "Email & SMS" then
MaximumCharacters = 160
endif

Mike55
 
I'm not really sure what it is that you're doing, but...

Assuming that your dropdownlist's values are actually text (and not some numeric equivalent, you could add something like this (probably as a function since the dropdown value can change and you'll need to call the code when it changes).

Code: 
function changeMaxChars()
    var oDropDown = document.getElementById("ddMessage");

    if (oDropDown.value == "Email")
    {
        MaximumCharacters = 500;
    }
    else if (oDropDown.value == "SMS" || oDropDown.value == "EMail & SMS")
    {
        MaximumCharacters = 160;
    }
}

On your dropdown list you'll need to add a javascript event handler (I think, if not then disregard) to fire the routine above, something like:

Code: 
<asp:dropdownlist id="ddMessage" runat="server" onchange="changeMaxChars();" />

onchange isn't an asp.net webcontrol event so there's no risk of conflicting with asp.net when you add that into the asp.net webcontrol declaration.

Good luck,
Paul

PS - That javascript you posted makes me cringe, especially the misuse and abuse of eval(). I'd recommend writing your own script if at all possible!
 
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