anagrams O(N) javascript without sort code example

Example 1: anagram program in javascript

function group_anagrams(arr) {
      let   sortedArr = arr.map(item => item.split('').sort().join(''));
      let setArr = new Set(sortedArr);
      let reducedObj = {};
      for (let setItem of setArr) {
        let indexArr = sortedArr.reduce((acc, cur, index) => {
          if (setItem === cur) {
            acc.push(index);
          }
          return acc;
        }, []);
        reducedObj[setItem] = indexArr;
      }
      let finalArr = [];
      for (let reduceItem in reducedObj) {
        finalArr.push(reducedObj[reduceItem].map(item => arr[item]));
      }
      return finalArr;
    }
    group_anagrams(['car','cra','rca', 'cheese','ab','ba']);

Example 2: anagram js

function isAnagram(stringA, stringB) {
  // Sanitizing
  stringA = stringA.toLowerCase().replace(/[\W_]+/g, "");
  stringB = stringB.toLowerCase().replace(/[\W_]+/g, "");

  // sorting
  const stringASorted = stringA.split("").sort().join("");
  const stringBSorted = stringB.split("").sort().join("");

  return stringASorted === stringBSorted;
}