1/**  2 * @param {string} s  3 * @return {string}  4 */  5var frequencySort = function(s) {
     6    const record = {};  7    const sArr = [...s];  8    sArr.forEach(value => {
     9        record[value] = (record[value] || 0) + 1; 10    }); 11 12    // a 出现的次数大于 b 13    return sArr.sort((a, b) => record[a] === record[b] ? 14        a.charCodeAt(0) - b.charCodeAt(0) : record[b] - record[a] 15    ).join(''); 16}; 17 18ensureEqual(frequencySort("tree"), "eert", 'test 1'); 19ensureEqual(frequencySort("trreee"), "eeerrt", 'test 2'); 20ensureEqual(frequencySort("abaccadeeefaafcc"), "aaaaacccceeeffbd", 'test 3'); 21ensureEqual(frequencySort("loveleetcode"), "eeeelloocdtv", 'test 4');