function rgb2hex(rgb) {
rgb = rgb.match(/^rgb\((\d+),(\d+),(\d+)\)$/);
function hex(x) {
return ("0" + parseInt(x).toString(16)).slice(-2);
}
return "#" + hex(rgb[1]) + hex(rgb[2]) + hex(rgb[3]);
}
var rgb = ‘rgb(255,255,255)‘;
console.log(rgb2hex(rgb));
原文：http://www.cnblogs.com/jdhu/p/4331994.html