Am using this javascript for restrict users to type only numbers and only one dot as decimal separator.
<script type="text/javascript">
function fun_AllowOnlyAmountAndDot(txt)
{
if(event.keyCode > 47 && event.keyCode < 58 || event.keyCode == 46)
{
var txtbx=document.getElementById(txt);
var amount = document.getElementById(txt).value;
var present=0;
var count=0;
if(amount.indexOf(".",present)||amount.indexOf(".",present+1));
{
// alert('0');
}
/*if(amount.length==2)
{
if(event.keyCode != 46)
return false;
}*/
do
{
present=amount.indexOf(".",present);
if(present!=-1)
{
count++;
present++;
}
}
while(present!=-1);
if(present==-1 && amount.length==0 && event.keyCode == 46)
{
event.keyCode=0;
//alert("Wrong position of decimal point not allowed !!");
return false;
}
if(count>=1 && event.keyCode == 46)
{
event.keyCode=0;
//alert("Only one decimal point is allowed !!");
return false;
}
if(count==1)
{
var lastdigits=amount.substring(amount.indexOf(".")+1,amount.length);
if(lastdigits.length>=2)
{
//alert("Two decimal places only allowed");
event.keyCode=0;
return false;
}
}
return true;
}
else
{
event.keyCode=0;
//alert("Only Numbers with dot allowed !!");
return false;
}
}
</script>
<td align="right">
<asp:TextBox ID="txtQ1gTarget" runat="server" Width="30px" CssClass="txtbx" MaxLength="6" onkeypress="return fun_AllowOnlyAmountAndDot(this);"></asp:TextBox>
</td>
But the onkeypress(this) event returns object required error in that function at this place
var amount = document.getElementById(txt).value;
What's my mistake here?
This is a great place to use regular expressions.
By using a regular expression, you can replace all that code with just one line.
You can use the following regex to validate your requirements:
[0-9]*\.?[0-9]*
In other words: zero or more numeric characters, followed by zero or one period(s), followed by zero or more numeric characters.
You can replace your code with this:
function validate(s) {
var rgx = /^[0-9]*\.?[0-9]*$/;
return s.match(rgx);
}
That code can replace your entire function!
Note that you have to escape the period with a backslash (otherwise it stands for 'any character').
For more reading on using regular expressions with javascript, check this out:
You can also test the above regex here:
Explanation of the regex used above:
The brackets mean "any character inside these brackets." You can use a hyphen (like above) to indicate a range of chars.
The *
means "zero or more of the previous expression."
[0-9]*
means "zero or more numbers"
The backslash is used as an escape character for the period, because period usually stands for "any character."
The ?
means "zero or one of the previous character."
The ^
represents the beginning of a string.
The $
represents the end of a string.
Starting the regex with ^
and ending it with $
ensures that the entire string adheres to the regex pattern.
Hope this helps!
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