对于所有函数式编程爱好者，这里有一个有点函数式的方法:)

const getHexColor = (rgbValue) =>
  rgbValue.replace("rgb(", "").replace(")", "").split(",")
    .map(colorValue => (colorValue > 15 ? "0" : "") + colorValue.toString(16))
    .reduce((acc, hexValue) => acc + hexValue, "#")

然后这样使用它:

const testRGB = "rgb(13,23,12)"
getHexColor(testRGB)

这是我的解决方案，也做touppercase使用一个参数和检查其他可能的空白和在提供的字符串大写。

var a = "rgb(10, 128, 255)";
var b = "rgb( 10, 128, 255)";
var c = "rgb(10, 128, 255 )";
var d = "rgb ( 10, 128, 255 )";
var e = "RGB ( 10, 128, 255 )";
var f = "rgb(10,128,255)";
var g = "rgb(10, 128,)";

var rgbToHex = (function () {
    var rx = /^rgb\s*\(\s*(\d+)\s*,\s*(\d+)\s*,\s*(\d+)\s*\)$/i;

    function pad(num) {
        if (num.length === 1) {
            num = "0" + num;
        }

        return num;
    }

    return function (rgb, uppercase) {
        var rxArray = rgb.match(rx),
            hex;

        if (rxArray !== null) {
            hex = pad(parseInt(rxArray[1], 10).toString(16)) + pad(parseInt(rxArray[2], 10).toString(16)) + pad(parseInt(rxArray[3], 10).toString(16));

            if (uppercase === true) {
                hex = hex.toUpperCase();
            }

            return hex;
        }

        return;
    };
}());

console.log(rgbToHex(a));
console.log(rgbToHex(b, true));
console.log(rgbToHex(c));
console.log(rgbToHex(d));
console.log(rgbToHex(e));
console.log(rgbToHex(f));
console.log(rgbToHex(g));

据jsfiddle

jsperf的速度比较

进一步的改进可以是trim() rgb字符串

var rxArray = rgb.trim().match(rx),

var hexDigits = new Array
        ("0","1","2","3","4","5","6","7","8","9","a","b","c","d","e","f"); 

//Function to convert rgb color to hex format
function rgb2hex(rgb) {
 rgb = rgb.match(/^rgb\((\d+),\s*(\d+),\s*(\d+)\)$/);
 return "#" + hex(rgb[1]) + hex(rgb[2]) + hex(rgb[3]);
}

function hex(x) {
  return isNaN(x) ? "00" : hexDigits[(x - x % 16) / 16] + hexDigits[x % 16];
 }

(源)

嗨，这是我的解决方案后，获得元素的颜色与Javascript

function rgb_hex(rgb_string_js){ //example: "rgb(102,54,255)"
  var new_rgb_list = rgb_string_js.replace("rgb(","").replace(")","").split(",");
  return ("#" + parseInt(new_rgb_list[0]).toString(16) + parseInt(new_rgb_list[1]).toString(16) + parseInt(new_rgb_list[2]).toString(16)); 
}

短

// c - color str e.g."rgb(12,233,43)", result color hex e.g. "#0ce92b"
let rgb2hex=c=>'#'+c.match(/\d+/g).map(x=>(+x).toString(16).padStart(2,0)).join``

// RGB -颜色STR，例如" RGB(12,233,43)"，结果颜色十六进制，例如“# 0 ce92b” 让rgb2hex = c = > ' # ' + c.match (\ d + / g) . map (x = > (+ x) .toString (16) .padStart (2,0)) . join ' ' console.log (rgb2hex(“rgb(12233年,43”);

更新@ErickPetru的rgba兼容性:

function rgb2hex(rgb) {
    rgb = rgb.match(/^rgba?\((\d+),\s*(\d+),\s*(\d+)(?:,\s*(\d+))?\)$/);
    function hex(x) {
        return ("0" + parseInt(x).toString(16)).slice(-2);
    }
    return "#" + hex(rgb[1]) + hex(rgb[2]) + hex(rgb[3]);
}

我更新了正则表达式，以匹配alpha值，如果定义，但不使用它。