findAnagramIndexes.js

const findAnagramIndexes = (w1, w2) => {
  let result = [];
  let control = [];
  
  for(let i = 0; i < w1.length; i++){
    if(control[i] === undefined) control[i] = w2.split('');
    for(let j = 0; j < control.length; j++) {
      if(control[j] === null) continue;
      if(Array.isArray(control[j]) && control[j].length === 0) continue;
      let indexOfLetter = control[j].indexOf(w1[i]);
      if(indexOfLetter > -1) {
        control[j].splice(indexOfLetter, 1);
      }else{
        control[j] = null;
      }
      if(Array.isArray(control[j]) && control[j].length === 0) {
        result.push(j);
      }
    }
  }
  
  return result;
}

const findAnagramIndexes2 = (w1, w2) => {
  const result = [];
  const sum = str => str.split('').reduce((acc, x) => {
    return acc + x.charCodeAt(0);
  }, 0);
  const haystack_len = w1.length;
  const needle_len = w2.length;
  const needle_sum = sum(w2);
  for(let i=0; i<=(haystack_len - needle_len); i++){
    if(sum(w1.substr(i, needle_len)) === needle_sum) result.push(i)
  }
  return result;
}

console.log(findAnagramIndexes("aabcdfccbavncccab", "abc"));