Convert base64 (no padding) to base10

convert.js

var ALPHABET = {'-': 62, '1': 53, '0': 52, '3': 55, '2': 54, '5': 57, '4': 56, '7': 59, '6': 58, '9': 61, '8': 60, 'A': 0, 'C': 2, 'B': 1, 'E': 4, 'D': 3, 'G': 6, 'F': 5, 'I': 8, 'H': 7, 'K': 10, 'J': 9, 'M': 12, 'L': 11, 'O': 14, 'N': 13, 'Q': 16, 'P': 15, 'S': 18, 'R': 17, 'U': 20, 'T': 19, 'W': 22, 'V': 21, 'Y': 24, 'X': 23, 'Z': 25, '_': 63, 'a': 26, 'c': 28, 'b': 27, 'e': 30, 'd': 29, 'g': 32, 'f': 31, 'i': 34, 'h': 33, 'k': 36, 'j': 35, 'm': 38, 'l': 37, 'o': 40, 'n': 39, 'q': 42, 'p': 41, 's': 44, 'r': 43, 'u': 46, 't': 45, 'w': 48, 'v': 47, 'y': 50, 'x': 49, 'z': 51};

function decode(s) {
    var n = 0;
    for(var i=0; i < s.length; i++) {
        var c = s.charAt(i);
        n = n * 64 + ALPHABET[c];
    }
    return n;
}
    
console.log(decode('EqfyK'));