How to parseInt a string with leading 0

Question

How to parseInt "09" into 9 ?

Gegenschein

Answer 1

include the radix:

parseInt("09", 10);

Subaltern

Answer 2

This has been driving me nuts -parseInt("02") works but not parseInt("09").

As others have said, the solution is to specify base 10:

parseInt("09", 10);

There's a good explanation for this behaviour here

... In Javascript numbers starting with zero are considered octal and there's no 08 or 09 in octal, hence the problem.

Ironclad

Answer 3

You can also do:

Number('09') => 9

This returns the integer 9 on IE7, IE8, FF3, FF4, and Chrome 10.

Cardiology

Answer 4

Re-implement the existing parseInt so that if it is called with one argument then "10" is automatically included as the second argument.

(function(){
  var oldParseInt = parseInt;
  parseInt = function(){
    if(arguments.length == 1)
    {
      return oldParseInt(arguments[0], 10);    
    }
    else
    {
      return oldParseInt.apply(this, arguments);
    }
  }
})();

Sitting

Answer 5

parseInt("09", 10);

or

parseInt(parseFloat("09"));

Noctambulism

Answer 6

parseInt("09",10);

returns 9 here.

It is odd.

alert(parseInt("09")); // shows 9. (tested with Opera 10)

Baran

@JonH: Right. Thanks for warning. Since he wrote string instead of String I was mistaken. – Baran

Depending on the browser and version parseInt("09") can return 0. It is a bug. – Noctambulism

@JonH: can you please check this: w3schools.com/jsref/jsref_parseInt.asp document.write(parseInt("010") also displays 10 here. – Baran

@JonH: It's not actually a bug. ECMAScript allows implementations to treat numbers with leading zeros as octal. Some implementations do, and some don't. – Haynie

@MatthewCrumley—an old comment but what the heck - ES5 removes that behaviour, so compliant browsers should treat parseInt('08') as base 10. – Cathartic