js rgb和16進制相互轉換

1.rgb to 16進制

function colorRGBtoHex(color) {
        var rgb = color.split(',');
        var r = parseInt(rgb[0]);
        var g = parseInt(rgb[1]);
        var b = parseInt(rgb[2]);
        var hex = "#" + ((1 << 24) + (r << 16) + (g << 8) + b).toString(16).slice(1);
        return hex;
    }

 2. 16進制 to rgb

function hex2rgb(a)
    {
        if (a == ""){
            return ""
        }
        a=a.substring(1);
        a=a.toLowerCase();
        b=new Array();
        for(x=0;x<3;x++){
            b[0]=a.substr(x*2,2);
            b[3]="0123456789abcdef";
            b[1]=b[0].substr(0,1);
            b[2]=b[0].substr(1,1);
            b[20+x]=b[3].indexOf(b[1])*16+b[3].indexOf(b[2]);
        }
        return "rgb(" +  b[20]+","+b[21]+","+b[22] + ")";
    }