CODEWITHSUNDEEP
javascriptarraysstring
justjs
justjs

Reputation: 11

Is it possible to use reduce with strings in JavaScript?

I wanted to know is it possible to use the reduce method on arrays with strings as well?

For ex: If I have an array like this: [ 'm', 'o', 'o', 'n' ] then I can reduce it to an object like this: { m: 1, o: 2, n: 1 }, that counts the occurrences of all characters in the string.
But if instead I had a string "moon" I wouldn't be able to use the reduce method with it.

I know I can write a custom implementation for reduce, but is there something simpler?

Upvotes: 1

Views: 1718

Answers (1)

Som Shekhar Mukherjee
Som Shekhar Mukherjee

Reputation: 8168

Yes, since Array.prototype.reduce is a generic method, it doesn't require it's this value to necessarily be an array. Meaning reduce is designed not only to work with arrays but to also work with other array-like values like strings.

And in order to use reduce with the string str, you can invoke it on the string by using Function.prototype.call.

const str = "moon";
const strCharCount = Array.prototype.reduce.call(
  str,
  (r, s) => {
    r[s] = (r[s] ?? 0) + 1;
    return r;
  },
  {}
);

console.log(strCharCount);

And if all of that didn't make any sense, you can also transform the string to an array and use reduce as you normally would.

const str = "moon";
const strCharCount = Array.from(str).reduce((r, s) => {
  r[s] = (r[s] ?? 0) + 1;
  return r;
}, {});

console.log(strCharCount);

Upvotes: 4

Related Questions