members是Objects的Array，首先您需要创建具有名称的Array-在这种情况下，您可以使用 .map ，然后将其转换为Array到String-为此，您可以使用 .join

members is Array of Objects, first you need to create Array with names - for this case you can use .map and then convert this Array to String - to do that you can use .join

var data = {
  "id": "123",
   "members": [
     { "id": 1, "name": "Andrew" },
     { "id": 2, "name": "Jim" }
   ]
};

var result = data.members.map(function (e) {
  return e.name;
}).join(', ');

console.log(result);