Tuesday, June 2, 2009

Convert jQuery RGB output to Hex Color

Please see my updated post:
Convert RGB(A) output to Hex Color

My current project uses Farbtastic which is a fantastic jQuery plugin which allows users to visually choose a color for an element. The problem I ran into was loading a default color from the element:

jQuery returns the element color in RGB format
document.write( $('#myElement').css('background-color') );
// outputs: rgb(34, 34, 34)

but Farbtastic uses the hex color format, just like the CSS.
#myElement { background-color: #222222 }
I found this really nice script (by R0bb13) which converts RGB to hex. This script requires the input variable to be in an array "[34,34,34]". In order to make the script use an RGB format "rgb(34,34,34)", I had to add one line to the script to remove the "rgb" and parenthesis and then convert (split) the result into an array...

Update #2 (allows entering an rgba value - opacity is ignored)

Updated (removing internal function):
//Function to convert hex format to a rgb color
function rgb2hex(orig){
 var rgb = orig.replace(/\s/g,'').match(/^rgba?\((\d+),(\d+),(\d+)/i);
 return (rgb && rgb.length === 4) ? "#" +
  ("0" + parseInt(rgb[1],10).toString(16)).slice(-2) +
  ("0" + parseInt(rgb[2],10).toString(16)).slice(-2) +
  ("0" + parseInt(rgb[3],10).toString(16)).slice(-2) : orig;
Here is an example of how to use this code with jQuery:
document.write( rgb2hex($('#myElement').css('background-color')) );
// outputs: #222222
Here is the original code from this post (not nearly as efficient as the updated script):
//Function to convert hex format to a rgb color
function rgb2hex(rgb) {
  var hexDigits = ["0","1","2","3","4","5","6","7","8","9","a","b","c","d","e","f"];
  rgb = rgb.match(/^rgb\((\d+),\s*(\d+),\s*(\d+)\)$/);
  function hex(x) {
    return isNaN(x) ? "00" : hexDigits[(x - x % 16) / 16] + hexDigits[x % 16];
  return "#" + hex(rgb[1]) + hex(rgb[2]) + hex(rgb[3]);