如何在golang中将切片附加到字节数组

I try to pass dynamic slic to this jsonstr slice

var catlist []string
var jsonStr = []byte(`{"categoryList":`+catlist+`}`)

But i'm getting this error

 invalid operation: "{\"categoryList\":" + catlist (mismatched types string and []string)

How can I fix this error

data := make(map[string]interface{})
        data["categoryList"] = catlist
        bytearray, err := json.Marshal(data)
        req, err := http.NewRequest("POST", url, bytes.NewBuffer(bytearray))

You are concating string and []string!! this is impossible! You must use json package: Package json