function getRGB(color){
  if(color.length == 7){
    var r = parseInt(color.substr(1,2),16);
    var g = parseInt(color.substr(3,2),16);
    var b = parseInt(color.substr(5,2),16);    
    return 'rgb('+r+','+g+','+b+')' ;
  }    
  else
    console.log('Enter correct value');
}
var a = getRGB('#f0f0f0');
if(!a){
 a = 'Enter correct value'; 
}

a;

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) }"

结合使用匿名函数和数组。地图为清洁工;更流线型的外观。

var write=function(str){document.body.innerHTML=JSON.stringify(str,null,' ');}; function hexToRgb(hex, asObj) { return (function(res) { return res == null ? null : (function(parts) { return !asObj ? parts : { r : parts[0], g : parts[1], b : parts[2] } }(res.slice(1,4).map(function(val) { return parseInt(val, 16); }))); }(/^#?([a-f\d]{2})([a-f\d]{2})([a-f\d]{2})$/i.exec(hex))); } function rgbToHex(r, g, b) { return (function(values) { return '#' + values.map(function(intVal) { return (function(hexVal) { return hexVal.length == 1 ? "0" + hexVal : hexVal; }(intVal.toString(16))); }).join(''); }(arguments.length === 1 ? Array.isArray(r) ? r : [r.r, r.g, r.b] : [r, g, b])) } // Prints: { r: 255, g: 127, b: 92 } write(hexToRgb(rgbToHex(hexToRgb(rgbToHex(255, 127, 92), true)), true)); body{font-family:monospace;white-space:pre}

相当简单的一行。用逗号分隔rgb，忽略非数字，转换为十六进制，填充0，并以hashbang结束。

Var yellow = 'rgb(255,255,0)'; Var rgb2hex = STR => "#"+ STR .split('，')。map(s => (s.replace(/\D/g， ")|0). tostring(16))。Map (s => s.length < 2 ?"0"+s: s).join("); console.log (rgb2hex(黄色));

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。

这可以用于从计算样式属性中获取颜色:

function rgbToHex(color) {
    color = ""+ color;
    if (!color || color.indexOf("rgb") < 0) {
        return;
    }

    if (color.charAt(0) == "#") {
        return color;
    }

    var nums = /(.*?)rgb\((\d+),\s*(\d+),\s*(\d+)\)/i.exec(color),
        r = parseInt(nums[2], 10).toString(16),
        g = parseInt(nums[3], 10).toString(16),
        b = parseInt(nums[4], 10).toString(16);

    return "#"+ (
        (r.length == 1 ? "0"+ r : r) +
        (g.length == 1 ? "0"+ g : g) +
        (b.length == 1 ? "0"+ b : b)
    );
}

// not computed 
<div style="color: #4d93bc; border: 1px solid red;">...</div> 
// computed 
<div style="color: rgb(77, 147, 188); border: 1px solid rgb(255, 0, 0);">...</div>

console.log( rgbToHex(color) ) // #4d93bc
console.log( rgbToHex(borderTopColor) ) // #ff0000

裁判:https://github.com/k-gun/so/blob/master/so_util.js