# How to convert an hex string to a Hex number

Discussion in 'Javascript' started by chirs, Dec 1, 2003.

1. ### chirsGuest

Hi,

I'd like to use a var to hold a Hex number. But in this code:

var a = "ffff00"

a is a string. var a=ffff00 will not work either. How can I put a
Hex number ffff00 into a var?

Thanks

Chris

chirs, Dec 1, 2003

2. ### Lasse Reichstein NielsenGuest

(chirs) writes:

> I'd like to use a var to hold a Hex number. But in this code:
>
> var a = "ffff00"
>
> a is a string. var a=ffff00 will not work either. How can I put a
> Hex number ffff00 into a var?

var a = 0xffff00;

In Javascript, and most other languages with a C like syntax,
hexadecimal numbers are written with a prefix "0x".

--
Lasse Reichstein Nielsen -
DHTML Death Colors: <URL:http://www.infimum.dk/HTML/rasterTriangleDOM.html>
'Faith without judgement merely degrades the spirit divine.'

Lasse Reichstein Nielsen, Dec 1, 2003

3. ### Douglas CrockfordGuest

> I'd like to use a var to hold a Hex number. But in this code:
>
> var a = "ffff00"
>
> a is a string. var a=ffff00 will not work either. How can I put a
> Hex number ffff00 into a var?

Buy a book. You can't program in total ignorance. I recommend Flanagan's
Definitive Guide (4th Ed) from O'Reilly.

Try

var a = 0xffff00;

http://www.crockford.com/javascript/javascript.html

Douglas Crockford, Dec 1, 2003
4. ### Dr John StocktonGuest

JRS: In article <>, seen
in news:comp.lang.javascript, chirs <> posted at Sun, 30
Nov 2003 21:36:27 :-
>
>I'd like to use a var to hold a Hex number.

Variables hold IEEE Doubles as the only form of number, except maybe in
future. You can, however, use Hex notation to specify the contents of a
variable.

> But in this code:
>
>var a = "ffff00"
>
>a is a string. var a=ffff00 will not work either. How can I put a
>Hex number ffff00 into a var?

var a = 0xffff00 // 1. to give a literal in Hex

var HS = "ffff00"

var a = +("0x"+HS) // 2. using existing string

var a = parseInt(HS, 16) // 3. normal, using existing string

Here 2 & 3 give different result with different illegal strings HS; try
"fated" & "defeat"; I prefer the former.

--