颜色字符串转换

 1 function rgb2hex(sRGB) {
 2     let re = /rgb\((\d+),\s*(\d+),\s*(\d+)\)/,
 3         ret = sRGB.match(re),
 4         head = "#";
 5     if(!ret) return sRGB;
 6     else {
 7         for(let i = 1; i < ret.length; i++) {
 8             let x = parseInt(ret[i]);
 9             if(x >= 0 && x <= 255) {
10                 head += x < 16 ? ‘0‘ + x.toString(16) : x.toString(16);
11             } else return sRGB;
12         }
13     }
14     return head
15 }