ECMAScript 6版本的Tim Down的答案

将RGB转换为十六进制

const rgbToHex = (r, g, b) => '#' + [r, g, b]。映射(x => { const十六进制= x.toString(16) 返回十六进制。长度=== 1 ?'0' + hex: hex }) . join () console.log(rgbToHex(0,51,255));/ / # 0033 ff的

将十六进制转换为RGB

返回一个数组[r, g, b]。工作也与速记十六进制三胞胎，如“#03F”。

const hexToRgb = hex => hex.replace (/ ^ # ? (\ d] [a - f) (\ d] [a - f) (\ d] [a - f) $ /我 ，(m, r, g, b) => '#' + r + r + g + g + b + b) .substring (1) .match (/ {2} / g)。 .map(x => parseInt(x, 16)) console.log(hexToRgb("#0033ff")) // [0,51,255] console.log(hexToRgb("#03f")) // [0,51,255]

附加:RGB到十六进制使用padStart()方法

const rgbToHex = (r, g, b) => '#' + [r, g, b] .map(x => x. tostring(16)。padStart (2, ' 0 ')) . join () console.log(rgbToHex(0,51,255));/ / # 0033 ff的

注意，这个答案使用了最新的ECMAScript特性，旧的浏览器不支持这些特性。如果希望此代码在所有环境中都能工作，则应该使用Babel来编译代码。

这段代码接受#fff和#ffffff变量和不透明度。

function hex2rgb(hex, opacity) {
        var h=hex.replace('#', '');
        h =  h.match(new RegExp('(.{'+h.length/3+'})', 'g'));

        for(var i=0; i<h.length; i++)
            h[i] = parseInt(h[i].length==1? h[i]+h[i]:h[i], 16);

        if (typeof opacity != 'undefined')  h.push(opacity);

        return 'rgba('+h.join(',')+')';
}

我假设您指的是html风格的十六进制符号，即#rrggbb。你的代码几乎是正确的，只是顺序颠倒了。它应该是:

var decColor = red * 65536 + green * 256 + blue;

此外，使用位移位可能会让它更容易阅读:

var decColor = (red << 16) + (green << 8) + blue;

hexToRgb的另一个版本:

function hexToRgb(hex) {
    var bigint = parseInt(hex, 16);
    var r = (bigint >> 16) & 255;
    var g = (bigint >> 8) & 255;
    var b = bigint & 255;

    return r + "," + g + "," + b;
}

编辑:3/28/2017 这是另一种似乎更快的方法

function hexToRgbNew(hex) {
  var arrBuff = new ArrayBuffer(4);
  var vw = new DataView(arrBuff);
  vw.setUint32(0,parseInt(hex, 16),false);
  var arrByte = new Uint8Array(arrBuff);

  return arrByte[1] + "," + arrByte[2] + "," + arrByte[3];
}

编辑:8/11/2017 经过更多测试后，上面的新方法并没有更快:(。虽然这是一种有趣的替代方式。

我给洛达什做了这个。它将一个RGB字符串，如“30,209,19”转换为其对应的十六进制字符串“#1ed113”:

var rgb = '30,209,19';

var hex = _.reduce(rgb.split(','), function(hexAccumulator, rgbValue) {
    var intColor = _.parseInt(rgbValue);

    if (_.isNaN(intColor)) {
        throw new Error('The value ' + rgbValue + ' was not able to be converted to int');
    }

    // Ensure a value such as 2 is converted to "02".
    var hexColor = _.padLeft(intColor.toString(16), 2, '0');

    return hexAccumulator + hexColor;
}, '#');

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 };
};