W1-D2-Cracking the Code review

crackingTheCode.js

/*
https://github.com/rich-at-thinkful/ft-curric-gists/blob/master/fundamentals/function-drills-2.md#cracking-the-code)

A code has been invented which replaces each character in a sentence with a 
five letter word. The first letter of each encoded word determines which of the remaining 
four characters contains the decoded character according to this table:

First letter	Character number
a	            2
b	            3
c	            4
d	            5
So for example, the encoded word 'cycle' would be decoded to the character 'l'. 
This is because the first letter is a 'c', so you look for the fourth character, which is 'l'.

If the first letter of the encoded word isn't 'a', 'b', 'c', or 'd' 
(for example 'mouse') this should be decoded to a space.

Write a function called decode which takes an encoded word as an argument, 
and returns the correct decoded character.

Use your function to decode the following message: 
'craft block argon meter bells brown croon droop'.

*/

//what is the input to the program
//craft

//what would be the output?
//f
/* //First try of the decode function
const decode = function(word){
    switch(word[0]){
        case 'a':
            return word[1];
        case 'b':
            return word[2];
        case 'c':
            return word[3];
        case 'd':
            return word[4];
        default:
            return '';
    }
};
*/
//Now that the function works, lets refactor it and make it better
//it should have the exact same output
const decode = function(word){
    const charCode = word[0].charCodeAt();
    //I want to decode a, b, c, d
    //anything before or after should not matter
    if(charCode < 97 || charCode > 100){
        return ' ';
    }
    return word[charCode - 96];
};

//Input:craft block argon meter bells brown croon droop
//Output: forloop

/* //first cut at the decodeString function
const decodeString = function(str){
    // extract words from string
    const wordArray = str.split(' '); //[craft, block, argon...]

    // send each word through the decode function to be decoded
    const decodedArray = wordArray.map(word => decode(word)); //function(word){decode(word)}

    //put each decoded letter together
    const decodedString = decodedArray.join('');
     //return the decoded string
    return decodedString;
};
*/
//lets refactor it
const decodeString = function(str){
    // extract words from string
    // send each word through the decode function to be decoded
    //put each decoded letter together
    //return the decoded string
    return str
            .split(' ')
            .map(word => decode(word))
            .join(''); 
     
};

//console.log(decode('block')); //f
console.log(decodeString('craft block argon meter bells brown croon droop')); //f