js实现16进制颜色转换成rgba格式

function colorRgb(str,opacity){
var sColor = str.toLowerCase();
if(sColor){
if(sColor.length === 4){
var sColorNew = "#";
for(var i=1; i<4; i+=1){
sColorNew += sColor.slice(i,i+1).concat(sColor.slice(i,i+1));
}
sColor = sColorNew;
}
//处理六位的颜色值
var sColorChange = [];
for(var i=1; i<7; i+=2){
sColorChange.push(parseInt("0x"+sColor.slice(i,i+2)));
}
return "rgba(" + sColorChange.join(",")+","+opacity + ")";
}else{
return sColor;
}
};