Q39 Is there a simple way to test if a variable is a number, e.g. test for entries like "1234a6789"?
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Q39 Is there a simple way to test if a variable is a number, e.g. test for entries like "1234a6789"?
There is code around (can't lay my hand on it at the moment) that can do lots of wonderful validation for numbers.
However, if it was me I would use something like the following:
<script language="JavaScript"><!--
function isan(string) {
if (string.length == 0)
return false;
for (var i=0;i < string.length;i++)
if ((string.substring(i,i+1) < '0') || (string.substring(i,i+1) > '9'))
return false;
return true;
}
//--></script>
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The following is a more efficient method, submitted by
Mike Crawford:
<script language="JavaScript"><!--
function validateInt(iString) {
// no leading 0s allowed
return (("" + parseInt(iString)) == iString);
}
//--></script>
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The following was submitted by Lalit C
There is single function isNaN (num).
- It returns true, if the parameter is NaN (Not A Number).
eg- No. with embeded blank or characters/symbols are NaN.
- It will return a number (if its a valid number), after trimming blanks on both sides
if (isNaN (myNumber)) {
// Not A Number
alert('Please enter a valid no.') ;
} else {
// A valid Number
// do some processing with the number
}
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The following was submitted by SAJEETH.K
Hmm... FAQ Knowledge Base Q39 holds valid only in case of INTEGERS. I hope the following code would work well for even floats (it also has provision for checking precision of float too, in this case 2 decimal digits). But, might be too straight forward instead of being technical. But,a working solution is what people demand..so it "WORKS"...
function validateInt(fieldValue) {
var found=0,i=0;
var allowedChars=".1234567890";
for (i=0;(i<fieldValue.length) && (found==0);i++) {
if (allowedChars.indexOf(fieldValue.charAt(i)) == -1) {
found=1;
alert('Error:: Field contains non-numeric. characters...');
return false;
}
}
var dotCount=0;
for(i=0;i<fieldValue.length;i++) {
if (fieldValue.charAt(i)=='.')
dotCount++;
}
if (dotCount >1) {
alert('Invalid field..contains more than one decimal chars');
return false;
} else if(dotCount==1) {
// Check for max. precision <=2
// GetIndex of '.'
if ((fieldValue.length - fieldValue.indexOf('.') ) > 3) {
alert('Limit precision to Max. 2 chars');
return false;
}
}
return true;
}
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The following was submitted by Alex Ivetic
Using regular expressions to test for valid numbers:
function isValidNumber(num){
// regular expression to test if field contains alpha
// expand accordingly to include any other non numeric character
isAlpha = /[(A-Z)|(a-z)]/ ;
if( isAlpha.test(num)) {
// not a number, return 0
return 0;
}
// num is a number, return 1
return 1;
}
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