|
|
Checking number using isNaN functionJavaScript has one important function isNaN() to check any data is number or string. This function isNaN() is remembered as short form is Is Not a Number. This function returns true if the data is string and returns false if the data is a number. Here is one simple example to check one string. We will use one if else condition check to display a message accordingly. Here is the code.
var my_string="This is a string";
if(isNaN(my_string)){
document.write ("this is not a number ");
}else{document.write ("this is a number ");
}
We will integrate this function to one JavaScript prompt. Here we will ask the user to enter a number. The value entered by user we will check by isNan function and display message accordingly. Here is the code.
var my_string = prompt("Please enter a number","");
document.write(my_string)
if(isNaN(my_string)){
document.write ("this is not a number ");
}else{document.write ("this is a number ");
}
Demo of isNan
Found anything wrong or wants to improve the code by adding more features? Post your short comment here or use the Forum
| |
| | Me2 | 07-03-2009 |
|---|
| Cool | | tcx | 11-10-2009 |
|---|
yes, agree,
this is very useful topic it helps me in project,
good concept not finding in other sites | | Dhaval Shingala | 25-02-2010 |
|---|
The simplest Way is Why u check entered input is Number or not
just check on Keypress Event is number or not
The Function for checking Is number is
function isNumberKey(B,C){if(!C){C=0}var A=(B.which)?B.which:event.keyCode;if(A>31 | | Rakesh Joshi | 16-04-2010 |
|---|
| I observed that isNaN has a flaw. If we enter a value with alphabets at the start, it will detect. But if it starts with a number and continues with alphabets or ends with alphabets, then isNaN will return false, meaning to say it is a number, which is not the desired output. Is there any other alternative? | | | 01-09-2010 |
|---|
| write a javascript code that will pop-up when an input of not a number is enter and return true when number data is enter. but without using in inbuild function such as isNan. | | angelito | 09-06-2012 |
|---|
| This is okay.. | | Ray | 30-08-2012 |
|---|
| Use Integer.parseInt("value") instead and put that in a try catch block. |
|
|
|
|
|
|
