Check if user entered a numeric character

[pedrodepacos]

I've written a client-side validation function (for a textbox) that checks if the key pressed by the user is numeric. I cannot get it to work properly, however. The following code does not prevent the user from entering a non-numeric character, but it does prevent the user from entering two non-numeric characters. For example if the user enters a "1" and the a "d", the textbox will display "1d". The next time the user presses a key, the "d" is removed and whatever character the user pressed replaces the "d". I don't want the textbox to display the character unless it is numeric.

'The following is entered in the codebehind

 
Dim txtQuantity As TextBox = e.Item.Cells(4).FindControl("txtQuantity") 
txtQuantity.Attributes.Add("onkeypress", "IsNumeric(" & txtQuantity.ClientID & ",'Integer')") 

'this is the javascript function called when the textbox's onkeypress event is fired

 
function IsNumeric(TextBox,strType) 
// check for valid numeric strings  
{ 
if (strType="Decimal") 
 { 
 var strValidChars = "0123456789."; 
 } 
else if (strType="Integer") 
 { 
 var strValidChars = "0123456789"; 
 } 
var strString; 
var strChar; 
strString=TextBox.value; 
for (i = 0; i < strString.length; i++) 
 { 
 strChar = strString.charAt(i); 
 if (strValidChars.indexOf(strChar) == -1) 
  { 
  TextBox.value = TextBox.value.substring(0, i); 
  TextBox.value.length = i 
  event.returnValue = false; 
  } 
 } 
} 

I'm not very proficient in Javascript so I'd appreciate any suggestions.

[gangstah]

Hi,

You could do something like

function isNumber(text){

 var goodChars = "0123456789.";

[/code]

 var isNum = true;

 var char;

// loop through the chars in the text you passed in

for (var idx = 0; text.length; idx++)

{

char = text.charAt(i);

// if the char isn't in the string of good 

// characters then exit returning false

if (goodChars.indexOf(char) == -1)

{

 return false;

}

}

// if you made it this far then your gold

return true;

}

}

Hope that helps.

[smokin]

You could easily achieve this using client side vbscript, which already has an IsNumeric function for you:
e.g
MyVar = 53 ' Assign a value.
MyCheck = IsNumeric(MyVar) ' Returns True.
MyVar = "459.95" ' Assign a value.
MyCheck = IsNumeric(MyVar) ' Returns True.
MyVar = "45 Help" ' Assign a value.
MyCheck = IsNumeric(MyVar) ' Returns False.

[garann]

Yet another approach (client-side Javascript):

// pass a reference to the field using: 
// onkeypress/onchange/onblur='chkNumeric(this)' 
function chkNumeric(obj) { 
    var val = ""; 
    //split the string every time a non-numeric is found 
    var vals = obj.value.split(/(\D)/); 
    for (var i=0;i<vals.length;i++)  
        //make your leftover characters, all numeric, into a string 
        val += vals[i]; 
    obj.value = val; 
... 
} 

hth,
g.

[pedrodepacos]

Thank you for all you suggestions, and I have now gotten it to work properly. I just have one more, slightly unrelated, question. Are there any characters that I need to replace, or exclude when adding a string (entered by the user) to a MS Access database?

[smokin]

The following characters need replacing when doing an insert into access db:
[ '

[pedrodepacos]

Thanks smokin, but what do I replace them with. I think I remember reading somewhere that you should replace ' with two apostrophes ''. Do I replace [ with '[?

When I get the string from the database, do I have to then replace the '' with a single '?