Candy Week 3: http://supernova-at.com/candy/3%20Baby%20Name/

week3.js

function getNames(input) {
	// Using the array index of map for the numbers
    var map = [
        // 0
        [''],
        // 1
        [''], 
        // 2
        ['a', 'b', 'c'], 
        // 3
        ['d', 'e', 'f'], 
        // 4
        ['g', 'h', 'i'], 
        // 5
        ['j', 'k', 'l'], 
        // 6
        ['m', 'n', 'o'], 
        // 7
        ['p', 'q', 'r', 's'], 
        // 8
        ['t', 'u', 'v'], 
        // 9
        ['w', 'x', 'y', 'z']
    ];
    
    // This is where we're going to store the individual outputs
    var permutations = [];
    
    // I'm assuming all valid inputs here, that's probably not a good thing to do
    
    // Get the digits
    var firstDigit = parseInt(input.charAt(0));
    var secondDigit = parseInt(input.charAt(1));
    var thirdDigit = parseInt(input.charAt(2));
    var fourthDigit = parseInt(input.charAt(3));
    
    // Get the arrays the digits map to
    var firstArray = map[firstDigit];
    var secondArray = map[secondDigit];
    var thirdArray = map[thirdDigit];
    var fourthArray = map[fourthDigit];
    
    // Determine the total number of permutations based on the length of the arrays
    var numPermutations = firstArray.length * secondArray.length * thirdArray.length * fourthArray.length;
    
    // Loop through the numbers from 1 to total number
    for (var i = 0; i < numPermutations; i++) {    
        // For each, figure out array index of each digit to target
        // We do this very similarly to how you'd figure out hours / minutes / seconds given a total number of seconds
        // For example, the first few are:
        // 0 = 0,0,0,0
        // 1 = 0,0,0,1
        // 2 = 0,0,0,2
        // 3 = 0,0,1,0
        // 4 = 0,0,1,1
        // 5 = 0,0,1,2
        // 6 = 0,0,2,0
        var firstIndex = Math.floor((i / (fourthArray.length * thirdArray.length * secondArray.length))) % firstArray.length;
        var secondIndex = Math.floor((i / (fourthArray.length * thirdArray.length))) % secondArray.length;
        var thirdIndex = Math.floor((i / fourthArray.length)) % thirdArray.length;
        var fourthIndex = i % fourthArray.length;
        
        console.log('indices', '' + firstIndex + '' + secondIndex + '' + thirdIndex + '' + fourthIndex);
        
        // Combine them all into an individual permutation
        var firstTarget = firstArray[firstIndex];
        var secondTarget = secondArray[secondIndex];
        var thirdTarget = thirdArray[thirdIndex];
        var fourthTarget = fourthArray[fourthIndex];
        
        // Add this permutation to the permutation list
        var thisPermutation = firstTarget.concat(secondTarget).concat(thirdTarget).concat(fourthTarget);
        console.log('this permutation', thisPermutation);
        permutations.push(thisPermutation);
    }
        
	// Return the list as a comma delimited string
	return permutations.join(', ');
}

var input = '1023'; // 7777 // 2345
var result = getNames(input);
console.log(result);

I'm not familiar with javascript, so I had some difficulty reading this. I definitely never would have thought to loop through all of the permutations this way. But your comments were super helpful and I'm pretty sure I understand what your are doing overall. Its been a long time since I have done any real math though, would you mind walking me through this part:

var firstIndex = Math.floor((i / (fourthArray.length * thirdArray.length * secondArray.length))) % firstArray.length;
var secondIndex = Math.floor((i / (fourthArray.length * thirdArray.length))) % secondArray.length;
var thirdIndex = Math.floor((i / fourthArray.length)) % thirdArray.length;
var fourthIndex = i % fourthArray.length;

I think one of my biggest limitations as a potential programmer is figuring out equations, especially how to effectively use the modulo operator.

I guess I am somewhat confused because when I translate it to Python I get floats rather than integers. I am guessing that what Math.floor does?