var data = "ashley, andy, juana"
var data = "Sports_ashley, Sports_andy, Sports_juana"
.replace should work to add sports before each comma. Below I have included an example.
var data = data.replace(/,/g , ", Sports_");
In that example using RegExp with g flag will replace all commas with
Sports, instead of just the first occurrence.
Then at the end you should just be able to append
Sports to the end like so.
data = "Sports_" + data;