哇。这些答案都不能处理分数的边缘情况，等等。当r, g, b为零时，位移版本也不起作用。

这是一个可以处理r g b是小数的版本。它对颜色之间的插值很有用，所以我也包括了这段代码。但它仍然不能处理r, g, b在0-255范围之外的情况

/**
 * Operates with colors.
 * @class Q.Colors
 */
 Q.Color = {
    /**
     * Get a color somewhere between startColor and endColor
     * @method toHex
     * @static
     * @param {String|Number} startColor 
     * @param {String|Number} endColor 
     * @param {String|Number} fraction 
     * @returns {String} a color as a hex string without '#' in front
     */
    toHex: function (r, g, b) {
        return [r, g, b].map(x => {
            const hex = Math.round(x).toString(16)
            return hex.length === 1 ? '0' + hex : hex
          }).join('');
    },
    /**
     * Get a color somewhere between startColor and endColor
     * @method between
     * @static
     * @param {String|Number} startColor 
     * @param {String|Number} endColor 
     * @param {String|Number} fraction 
     * @returns {String} a color as a hex string without '#' in front
     */
    between: function(startColor, endColor, fraction) {
        if (typeof startColor === 'string') {
            startColor = parseInt(startColor.replace('#', '0x'), 16);
        }
        if (typeof endColor === 'string') {
            endColor = parseInt(endColor.replace('#', '0x'), 16);
        }
        var startRed = (startColor >> 16) & 0xFF;
        var startGreen = (startColor >> 8) & 0xFF;
        var startBlue = startColor & 0xFF;
        var endRed = (endColor >> 16) & 0xFF;
        var endGreen = (endColor >> 8) & 0xFF;
        var endBlue = endColor & 0xFF;
        var newRed = startRed + fraction * (endRed - startRed);
        var newGreen = startGreen + fraction * (endGreen - startGreen);
        var newBlue = startBlue + fraction * (endBlue - startBlue);
        return Q.Color.toHex(newRed, newGreen, newBlue);
    },
    /**
     * Sets a new theme-color on the window
     * @method setWindowTheme
     * @static
     * @param {String} color in any CSS format, such as "#aabbcc"
     * @return {String} the previous color
     */
    setWindowTheme: function (color) {
        var meta = document.querySelector('meta[name="theme-color"]');
        var prevColor = null;
        if (meta) {
            prevColor = meta.getAttribute('content');
        }
        if (color) {
            if (!meta) {
                meta = document.createElement('meta');
                meta.setAttribute('name', 'theme-color');
            }
            meta.setAttribute('content', color);
        }
        return prevColor;
    },
    /**
     * Gets the current window theme color
     * @method getWindowTheme
     * @static
     * @param {String} color in any CSS format, such as "#aabbcc"
     * @return {String} the previous color
     */
    getWindowTheme: function () {
        var meta = document.querySelector('meta[name="theme-color"]');
        return meta.getAttribute('content');
    }
}

以下是我的看法:

function rgbToHex(red, green, blue) {
  const rgb = (red << 16) | (green << 8) | (blue << 0);
  return '#' + (0x1000000 + rgb).toString(16).slice(1);
}

function hexToRgb(hex) {
  const normal = hex.match(/^#([0-9a-f]{2})([0-9a-f]{2})([0-9a-f]{2})$/i);
  if (normal) return normal.slice(1).map(e => parseInt(e, 16));

  const shorthand = hex.match(/^#([0-9a-f])([0-9a-f])([0-9a-f])$/i);
  if (shorthand) return shorthand.slice(1).map(e => 0x11 * parseInt(e, 16));

  return null;
}

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。

如果你需要比较两个颜色值(给定为RGB，名称颜色或十六进制值)或转换为hex使用HTML5 canvas对象。

var canvas = document.createElement("canvas");
var ctx = this.canvas.getContext('2d');

ctx.fillStyle = "rgb(pass,some,value)";
var temp =  ctx.fillStyle;
ctx.fillStyle = "someColor";

alert(ctx.fillStyle == temp);

试(奖金)

let hex2rgb= c=> `rgb(${c.match(/\w\w/g).map(x=>+`0x${x}`)})`
let rgb2hex=c=>'#'+c.match(/\d+/g).map(x=>(+x).toString(16).padStart(2,0)).join``

让hex2rgb = c = > ' rgb ($ {c.match (w / \ \ w / g) . map (x = > + 0 x $ {x})})”; 让rgb2hex = c = > ' # ' + c.match (\ d + / g) . map (x = > (+ x) .toString (16) .padStart (2,0)) . join '; / /测试 console.log('#0080C0—>'，hex2rgb('#0080C0')); console.log(“rgb(0, 128, 192)——>”,rgb2hex(的rgb (0, 128, 192)));

基于@ michazperzhaakowski的回答(EcmaScipt 6)和他基于Tim Down的回答的回答

我写了一个转换hexToRGB函数的修改版本，增加了安全检查r/g/b颜色组件是否在0-255之间，而且函数可以接受数字r/g/b参数或字符串r/g/b参数，如下所示:

 function rgbToHex(r, g, b) {
     r = Math.abs(r);
     g = Math.abs(g);
     b = Math.abs(b);

     if ( r < 0 ) r = 0;
     if ( g < 0 ) g = 0;
     if ( b < 0 ) b = 0;

     if ( r > 255 ) r = 255;
     if ( g > 255 ) g = 255;
     if ( b > 255 ) b = 255;

    return '#' + [r, g, b].map(x => {
      const hex = x.toString(16);
      return hex.length === 1 ? '0' + hex : hex
    }).join('');
  }

为了安全地使用这个函数——你应该检查传递的字符串是否是真正的rbg字符串颜色——例如，一个非常简单的检查可以是:

if( rgbStr.substring(0,3) === 'rgb' ) {

  let rgbColors = JSON.parse(rgbStr.replace('rgb(', '[').replace(')', ']'))
  rgbStr = this.rgbToHex(rgbColors[0], rgbColors[1], rgbColors[2]);

  .....
}