1
var frequencySort = function (s) {
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  let obj = {};
3
  for (const i of s) {
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    obj[i] = (obj[i] || 0) + 1;
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  }
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  let sorted = Object.entries(obj).sort((a, b) => b[1] - a[1]);
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  return sorted.map((e) => e[0].repeat(e[1])).join("");
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};