javascript convert set to comma separated string - IE11

Question

I'm having issues to convert a Set to a comma separated string in IE11, the below works fine in chrome, but IE11 doesn't like Array.from.

let a = new Set();
a.add("a");
a.add("b");

console.log(Array.from(a).join(","));

To get a work around I'm doing:

let aArray = [];                        
let pushToArray = function(val) {
  aArray.push(val);
};
a.forEach(pushToArray);

console.log(aArray.toString());

Any suggestion on how to do the above better that works in IE11?

Answer 1

It could be better, if you don't even build an array from it, only create the string using concatenation:

let a = new Set();
a.add("a");
a.add("b");

function SetToString(set, delim){
  let str = '';
  set.forEach(function(elem){
    str += elem + delim
  });
  return str
}
console.log(SetToString(a, ','));

The only issue with this approach is that it will add a comma at the end as well.

To avoid this, you have two ways:

• Remove the last comma using .slice(0, -1)

  let a = new Set();
  a.add("a");
  a.add("b");
  
  function SetToString(set, delim){
    let str = '';
    set.forEach(function(elem){
      str += elem + delim
    });
    return str.slice(0, -1)
  }
  console.log(SetToString(a, ','));
  

• Count elements, and omit comma for the last

  let a = new Set();
  a.add("a");
  a.add("b");
  
  function SetToString(set, delim){
    let str = '';
    let i = 0;
    let size = set.size;
    set.forEach(function(elem){
      str += elem
      if(i++ < size - 1) str += delim
    });
    return str
  }
  console.log(SetToString(a, ','));