Tim Down给出的最高评级的答案提供了我所能看到的转换为RGB的最佳解决方案。我更喜欢这个十六进制转换的解决方案，因为它为转换到十六进制提供了最简洁的边界检查和零填充。

function RGBtoHex (red, green, blue) {
  red = Math.max(0, Math.min(~~red, 255));
  green = Math.max(0, Math.min(~~green, 255));
  blue = Math.max(0, Math.min(~~blue, 255));

  return '#' + ('00000' + (red << 16 | green << 8 | blue).toString(16)).slice(-6);
};

左移'<<'和或'|'操作符的使用也使这成为一个有趣的解决方案。

2021年版

你可以简单地使用rgb-十六进制和十六进制-rgb，因为它是经过战斗测试的，有多个选项，在其他解决方案中是不可用的。

我最近正在构建一个颜色选择器&这2个包派上用场。

使用

rgb-hex

import rgbHex from 'rgb-hex';

rgbHex(65, 131, 196);
//=> '4183c4'

rgbHex('rgb(40, 42, 54)');
//=> '282a36'

rgbHex(65, 131, 196, 0.2);
//=> '4183c433'

rgbHex(40, 42, 54, '75%');
//=> '282a36bf'

rgbHex('rgba(40, 42, 54, 75%)');
//=> '282a36bf'

hex-rgb

import hexRgb from 'hex-rgb';

hexRgb('4183c4');
//=> {red: 65, green: 131, blue: 196, alpha: 1}

hexRgb('#4183c4');
//=> {red: 65, green: 131, blue: 196, alpha: 1}

hexRgb('#fff');
//=> {red: 255, green: 255, blue: 255, alpha: 1}

hexRgb('#22222299');
//=> {red: 34, green: 34, blue: 34, alpha: 0.6}

hexRgb('#0006');
//=> {red: 0, green: 0, blue: 0, alpha: 0.4}

hexRgb('#cd2222cc');
//=> {red: 205, green: 34, blue: 34, alpha: 0.8}

hexRgb('#cd2222cc', {format: 'array'});
//=> [205, 34, 34, 0.8]

hexRgb('#cd2222cc', {format: 'css'});
//=> 'rgb(205 34 34 / 80%)'

hexRgb('#000', {format: 'css'});
//=> 'rgb(0 0 0)'

hexRgb('#22222299', {alpha: 1});
//=> {red: 34, green: 34, blue: 34, alpha: 1}

hexRgb('#fff', {alpha: 0.5});
//=> {red: 255, green: 255, blue: 255, alpha: 0.5}

rgb字符串到十六进制字符串的可读联机程序:

rgb = "rgb(0,128,255)"
hex = '#' + rgb.slice(4,-1).split(',').map(x => (+x).toString(16).padStart(2,0)).join('')

返回这里“#0080ff”。

HEX转RGB (ES6) +测试[2022]

convertHexToRgb.ts:

/**
 * RGB color regexp
 */
export const RGB_REG_EXP = /rgb\((\d{1,3}), (\d{1,3}), (\d{1,3})\)/;

/**
 * HEX color regexp
 */
export const HEX_REG_EXP = /^#?(([\da-f]){3}|([\da-f]){6})$/i;

/**
 * Converts HEX to RGB.
 *
 * Color must be only HEX string and must be:
 *  - 7-characters starts with "#" symbol ('#ffffff')
 *  - or 6-characters without "#" symbol ('ffffff')
 *  - or 4-characters starts with "#" symbol ('#fff')
 *  - or 3-characters without "#" symbol ('fff')
 *
 * @function { color: string => string } convertHexToRgb
 * @return { string } returns RGB color string or empty string
 */
export const convertHexToRgb = (color: string): string => {
    const errMessage = `
    Something went wrong while working with colors...
    
    Make sure the colors provided to the "PieDonutChart" meet the following requirements:
    
    Color must be only HEX string and must be 
    7-characters starts with "#" symbol ('#ffffff')
    or 6-characters without "#" symbol ('ffffff')
    or 4-characters starts with "#" symbol ('#fff')
    or 3-characters without "#" symbol ('fff')
    
    - - - - - - - - -
    
    Error in: "convertHexToRgb" function
    Received value: ${color}
  `;

    if (
        !color
        || typeof color !== 'string'
        || color.length < 3
        || color.length > 7
    ) {
        console.error(errMessage);
        return '';
    }

    const replacer = (...args: string[]) => {
        const [
            _,
            r,
            g,
            b,
        ] = args;

        return '' + r + r + g + g + b + b;
    };

    const rgbHexArr = color
        ?.replace(HEX_REG_EXP, replacer)
        .match(/.{2}/g)
        ?.map(x => parseInt(x, 16));

    /**
     * "HEX_REG_EXP.test" is here to create more strong tests
     */
    if (rgbHexArr && Array.isArray(rgbHexArr) && HEX_REG_EXP.test(color)) {
        return `rgb(${rgbHexArr[0]}, ${rgbHexArr[1]}, ${rgbHexArr[2]})`;
    }

    console.error(errMessage);
    return '';
};

我正在使用Jest进行测试

color.spec.ts

describe('function "convertHexToRgb"', () => {
    it('returns a valid RGB with the provided 3-digit HEX color: [color = \'fff\']', () => {
        expect.assertions(2);

        const { consoleErrorMocked }  = mockConsole();
        const rgb = convertHexToRgb('fff');

        expect(RGB_REG_EXP.test(rgb)).toBeTruthy();
        expect(consoleErrorMocked).not.toHaveBeenCalled();
    });

    it('returns a valid RGB with the provided 3-digit HEX color with hash symbol: [color = \'#fff\']', () => {
        expect.assertions(2);

        const { consoleErrorMocked }  = mockConsole();
        const rgb = convertHexToRgb('#fff');

        expect(RGB_REG_EXP.test(rgb)).toBeTruthy();
        expect(consoleErrorMocked).not.toHaveBeenCalled();
    });

    it('returns a valid RGB with the provided 6-digit HEX color: [color = \'ffffff\']', () => {
        expect.assertions(2);

        const { consoleErrorMocked }  = mockConsole();
        const rgb = convertHexToRgb('ffffff');

        expect(RGB_REG_EXP.test(rgb)).toBeTruthy();
        expect(consoleErrorMocked).not.toHaveBeenCalled();
    });

    it('returns a valid RGB with the provided 6-digit HEX color with the hash symbol: [color = \'#ffffff\']', () => {
        expect.assertions(2);

        const { consoleErrorMocked }  = mockConsole();
        const rgb = convertHexToRgb(TEST_COLOR);

        expect(RGB_REG_EXP.test(rgb)).toBeTruthy();
        expect(consoleErrorMocked).not.toHaveBeenCalled();
    });

    it('returns an empty string when the provided value is not a string: [color = 1234]', () => {
        expect.assertions(2);

        const { consoleErrorMocked }  = mockConsole();

        // @ts-ignore
        const rgb = convertHexToRgb(1234);

        expect(rgb).toBe('');
        expect(consoleErrorMocked).toHaveBeenCalledTimes(1);
    });

    it('returns an empty string when the provided color is too short: [color = \'FF\']', () => {
        expect.assertions(2);

        const { consoleErrorMocked }  = mockConsole();

        const rgb = convertHexToRgb('FF');

        expect(rgb).toBe('');
        expect(consoleErrorMocked).toHaveBeenCalledTimes(1);
    });

    it('returns an empty string when the provided color is too long: [color = \'#fffffff\']', () => {
        expect.assertions(2);

        const { consoleErrorMocked }  = mockConsole();

        const rgb = convertHexToRgb('#fffffff');

        expect(rgb).toBe('');
        expect(consoleErrorMocked).toHaveBeenCalledTimes(1);
    });

    it('returns an empty string when the provided value is looks like HEX color string but has invalid symbols: [color = \'#fffffp\']', () => {
        expect.assertions(2);

        const { consoleErrorMocked }  = mockConsole();
        const rgb = convertHexToRgb('#fffffp');

        expect(rgb).toBe('');
        expect(consoleErrorMocked).toHaveBeenCalledTimes(1);
    });

    it('returns an empty string when the provided value is invalid: [color = \'*\']', () => {
        expect.assertions(2);

        const { consoleErrorMocked }  = mockConsole();

        const rgb = convertHexToRgb('*');

        expect(rgb).toBe('');
        expect(consoleErrorMocked).toHaveBeenCalledTimes(1);
    });

    it('returns an empty string when the provided value is undefined: [color = undefined]', () => {
        expect.assertions(2);

        const { consoleErrorMocked }  = mockConsole();

        // @ts-ignore
        const rgb = convertHexToRgb(undefined);

        expect(rgb).toBe('');
        expect(consoleErrorMocked).toHaveBeenCalledTimes(1);
    });
});

测试结果:

function "convertHexToRgb"
    √ returns a valid RGB with the provided 3-digit HEX color: [color = 'fff']
    √ returns a valid RGB with the provided 3-digit HEX color with hash symbol: [color = '#fff']
    √ returns a valid RGB with the provided 6-digit HEX color: [color = 'ffffff']
    √ returns a valid RGB with the provided 6-digit HEX color with the hash symbol: [color = '#ffffff']
    √ returns an empty string when the provided value is not a string: [color = 1234]
    √ returns an empty string when the provided color is too short: [color = 'FF']
    √ returns an empty string when the provided color is too long: [color = '#fffffff']
    √ returns an empty string when the provided value is looks like HEX color string but has invalid symbols: [color = '#fffffp']
    √ returns an empty string when the provided value is invalid: [color = '*']
    √ returns an empty string when the provided value is undefined: [color = undefined]

和mockConsole:

export const mockConsole = () => {
  const consoleError = jest.spyOn(console, 'error').mockImplementationOnce(() => undefined);
  return { consoleError };
};

上面的一个干净的咖啡脚本版本(谢谢@TimDown):

rgbToHex = (rgb) ->
    a = rgb.match /\d+/g
    rgb  unless a.length is 3
    "##{ ((1 << 24) + (parseInt(a[0]) << 16) + (parseInt(a[1]) << 8) + parseInt(a[2])).toString(16).slice(1) }"

(2017) SIMPLE ES6组合箭头函数

我忍不住要把这个分享给那些可能正在使用ES6编写一些现代函数/复合js的人。下面是我在一个颜色模块中使用的一些光滑的单行程序，它为数据可视化做颜色插值。

注意，这根本不处理alpha通道。

const arrayToRGBString = rgb => `rgb(${rgb.join(',')})`;
const hexToRGBArray = hex => hex.match(/[A-Za-z0-9]{2}/g).map(v => parseInt(v, 16));
const rgbArrayToHex = rgb => `#${rgb.map(v => v.toString(16).padStart(2, '0')).join('')}`;
const rgbStringToArray = rgb => rgb.match(/^rgb\((\d+),\s*(\d+),\s*(\d+)\)$/).splice(1, 3)
  .map(v => Number(v));
const rgbStringToHex = rgb => rgbArrayToHex(rgbStringToArray(rgb));

顺便说一句，如果你喜欢这种风格/语法，我写了一个全彩色模块(modern-color)，你可以从npm中获取。我这样做，所以我可以使用道具getter转换和解析几乎任何东西(Color.parse(anything))。如果你和我一样对颜色很敏感的话，值得一看。