You actually have one capture group that will match multiple times. Not multiple capture groups.

javascript (js) solution:

let string = "HI,THERE,TOM";
let myRegexp = /([A-Z]+),?/g;       //modify as you like
let match = myRegexp.exec(string);  //js function, output described below
while(match!=null){                 //loops through matches
    console.log(match[1]);          //do whatever you want with each match
    match = myRegexp.exec(bob);     //find next match
}

Output:

HI
THERE
TOM

Syntax:

// matched text: match[0]
// match start: match.index
// capturing group n: match[n]

As you can see, this will work for any number of matches.

You actually have one capture group that will match multiple times. Not multiple capture groups.

javascript (js) solution:

let string = "HI,THERE,TOM";
let myRegexp = /([A-Z]+),?/g;       // modify as you like
let match = myRegexp.exec(string);  // js function, output described below
while (match != null) {             // loops through matches
  console.log(match[1]);            // do whatever you want with each match
  match = myRegexp.exec(string);    // find next match
}

Syntax:

// matched text: match[0]
// match start: match.index
// capturing group n: match[n]

As you can see, this will work for any number of matches.