定义一个新的rgb函数，然后用eval执行字符串

function rgb2hex(sRGB) {
    try{
        return eval(sRGB)
    }
    catch(err){
        return sRGB
    }
}
function rgb(r,g,b){
    let rH=r.toString(16)
    let gH=g.toString(16)
    let bH=b.toString(16)
    rH=rH.length==1?'0'+rH:rH
    gH=gH.length==1?'0'+gH:gH
    bH=bH.length==1?'0'+bH:bH
    return "#"+rH+gH+bH
}