RGB to hex and hex to RGB

Question

How to convert colors in RGB format to hex format and vice versa?

For example, convert '#0080C0' to (0, 128, 192).

Answer 1

Note: both versions of rgbToHex expect integer values for r, g and b, so you'll need to do your own rounding if you have non-integer values.

The following will do to the RGB to hex conversion and add any required zero padding:

function componentToHex(c) {   var hex = c.toString(16);   return hex.length == 1 ? "0" + hex : hex; }  function rgbToHex(r, g, b) {   return "#" + componentToHex(r) + componentToHex(g) + componentToHex(b); }  alert(rgbToHex(0, 51, 255)); // #0033ff

Converting the other way:

function hexToRgb(hex) {   var result = /^#?([a-f\d]{2})([a-f\d]{2})([a-f\d]{2})$/i.exec(hex);   return result ? {     r: parseInt(result[1], 16),     g: parseInt(result[2], 16),     b: parseInt(result[3], 16)   } : null; }  alert(hexToRgb("#0033ff").g); // "51";

Finally, an alternative version of rgbToHex(), as discussed in @casablanca's answer and suggested in the comments by @cwolves:

function rgbToHex(r, g, b) {   return "#" + ((1 << 24) + (r << 16) + (g << 8) + b).toString(16).slice(1); }  alert(rgbToHex(0, 51, 255)); // #0033ff

Update 3 December 2012

Here's a version of hexToRgb() that also parses a shorthand hex triplet such as "#03F":

function hexToRgb(hex) {   // Expand shorthand form (e.g. "03F") to full form (e.g. "0033FF")   var shorthandRegex = /^#?([a-f\d])([a-f\d])([a-f\d])$/i;   hex = hex.replace(shorthandRegex, function(m, r, g, b) {     return r + r + g + g + b + b;   });    var result = /^#?([a-f\d]{2})([a-f\d]{2})([a-f\d]{2})$/i.exec(hex);   return result ? {     r: parseInt(result[1], 16),     g: parseInt(result[2], 16),     b: parseInt(result[3], 16)   } : null; }  alert(hexToRgb("#0033ff").g); // "51"; alert(hexToRgb("#03f").g); // "51";