Count the occurrence of every alphabet from a string in Javascript

I have seen similar questions like this asked before, such as counting characters in a given string. However when it comes to comparing given string to the letters of the alphabet and returning an object with occurences such as:

const letters = ["a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"]

const sampleString = "a bee";

const results = {
 a: 1,
 b: 1,
 c: 0,
 d: 0,
 e: 2,
 f: 0,
 ...
}

>Solution :

We can use Array.reduce(),
to count letters in the sampleString.

We start by creating a letterMap to specify all valid letters to be counted.

In the reduce loop, we only increment letters that are present in the letterMap, using the (c in acc) expression.

const letters = ["a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"]

const sampleString = "a bee";

const letterMap = letters.reduce((acc, c) => { 
    acc[c] = 0; 
    return acc; 
}, {});

const result = [...sampleString].reduce((acc, c) => {
    if (c in acc) acc[c]++;
    return acc;
}, letterMap);

console.log('Result:', result)
 

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