`indexOf` vs `Map`

firstUniqChar.js

function firstUniqCharWithHashMap(str) {
  const map = new Map();
  
  for (let i = 0; i < str.length; i++) {
    const char = str.charAt(i);
    if (!map.has(char)) {
      map.set(char, [i, 1]);
    } else {
      map.set(char, [i, map.get(char) + 1]);
    }
  }
  
  for (let entry of map.values()) {
    if (entry[1] == 1) {
      return entry[0];
    }
  }
  
  return -1;
}

function firstUniqCharWithIndexOf(str) {
  const arr = str.split("");
  
  for (let i = 0; i < arr.length; i++) {
    const idx = arr.indexOf(arr[i]);
    const lastIdx = arr.lastIndexOf(arr[i]);
    if (idx === lastIdx) {
      return i;
    }
  }
  
  return -1;
}

const t0 = performance.now();
for (let i = 0; i < 1000000; i++) {
  firstUniqCharWithHashMap("loveleetcode");
}
const t1 = performance.now();

const t2 = performance.now();
for (let i = 0; i < 1000000; i++) {
  firstUniqCharWithIndexOf("loveleetcode");
}
const t3 = performance.now();

console.log('HashMap: ' + (t1 - t0) + 'ms');
console.log('IndexOf: ' + (t3 - t2) + 'ms');