Check that variable is a number

Question

How can I check that a variable is a number, either an integer or a string digit?

In PHP I could do:

if (is_int($var)) {
    echo \'$var is integer\'         


        

Answer 1

You should use: $.isNumeric( i )

jQuery.isNumeric API

Answer 2

Be aware that empty string '' and ' ' will be considered as number by isNaN and isFinite.

Answer 3

See isNan

EDIT: Please look at what Christoph has suggested above. It makes sense to use isFinite as suggested.

Answer 4

You should use

simple way to check whether given value is number by using "if condition"

function isInteger(value)      
{       
    num=value.trim();         
    return !(value.match(/\s/g)||num==""||isNaN(num)||(typeof(value)=='number');        
}

it will return true if the value which we are passing is an integer..

solved for     
value=""      //false null     
value="12"    //true only integers       
value="a"     //false     
value=" 12"   //false      
value="12 "   //false         
value=" "     //false space        
value="$12"   //false special characters 
value="as12"    //false

Answer 5

The javascript function isNaN(variable) should do the trick. It returns true if the data is not a number.

Answer 6

You should use:

var x = 23;
var y = 34hhj;

isNaN(x); 
isNaN(y); 

It will return true if its string and false if its a number.