颜色rgba、16进制、10进制互相装换

rgba转16进制：

function RGBToHex(rgb){
   var regexp = /[0-9]{0,3}/g;
   var re = rgb.match(regexp);//利用正则表达式去掉多余的部分，将rgb中的数字提取
   var hexColor = "#"; var hex = ['0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'];
   for (var i = 0; i < re.length; i++) {
        var r = null, c = re[i], l = c;
        var hexAr = [];
        while (c > 16){
              r = c % 16;
              c = (c / 16) >> 0;
              hexAr.push(hex[r]);
         } hexAr.push(hex[c]);
         if(l < 16&&l != ""){
             hexAr.push(0)
         }
       hexColor += hexAr.reverse().join('');
    }
   //alert(hexColor)
   return hexColor;
} 

16进制转rgba：

var util = {
    cutHex: function (hex) {
        return hex.charAt(0) == "#" ? hex.substring(1, 7) : hex;
    },
    hexToR: function (hex) {
        return parseInt((util.cutHex(hex)).substring(0, 2), 16)
    },
    hexToG: function (hex) {
        return parseInt((util.cutHex(hex)).substring(2, 4), 16)
    },
    hexToB: function (hex) {
        return parseInt((util.cutHex(hex)).substring(4, 6), 16)
    },
    hexToRgba: function (hex) {
        return 'rgba('+util.hexToR(hex)+','+util.hexToG(hex)+','+util.hexToB(hex)+',0.1)';
    }
};

10进制转rgba（转自网络，未验证）：

方法一：

function getColor(number) {
        let color = number;
        const blue = parseInt(color % 0x100, 10);
        color = color >>> 8;
        const green = parseInt(color % 0x100, 10);
        color = color >>> 8;
        const red = parseInt(color % 0x100, 10);
        const alpha = (parseInt(color >>> 8, 10) / 0xFF).toFixed(1);
        return `rgba(${red}, ${green}, ${blue}, ${alpha})`;
    }

方法二：

function getColor(number) {
    const alpha = number >> 24 & 0xff;
    const red = number >> 16 & 0xff;
    const green = number >> 8 & 0xff;
    const blue = number & 0xff;
    return `rgba(${red}, ${green}, ${blue}, ${alpha})`;
}