Convert and add the letters into number

numerology.js

const letterExhange = {
                        a: 1,
                        b: 2,
                        c: 3,
                        d: 4,
                        e: 5,
                        f: 6,
                        g: 7,
                        h: 8,
                        i: 9,
                        j: 10,
                        k: 11,
                        l: 12,
                        m: 13,
                        n: 14,
                        o: 15,
                        p: 16,
                        q: 17,
                        r: 18,
                        s: 19,
                        t: 20,
                        u: 21,
                        v: 22,
                        w: 23,
                        x: 24,
                        y: 25,
                        z: 26
                }

function calculate(value = ""){

        value = value.replace(/\s/g,"").toLowerCase(); // Remove All spaces then convert into lowercase letters

        let result = 0

        for (let i = 0; i < value.length; i++) {
                const letter = value[i];

                result += letterExhange[letter] || 0; // if the letter is not on the letterExchange the default will be 0
        }

        return result
}

const input = " a bc de ";
console.log(calculate(input)); // 15