Recursive-descent parser to find the second occurrence of the string 'ABC' in a string.

useless.js

var aPosition = -1,
    position = 0,
    count = 0,
    desiredCount = 2,
    string = 'XYZ 123 ABC 456 ABC 789 ABC',
    tokens = string.split('');

var parse = function(tokens)
{
    if (tokens[0] === 'A')
    {
        return a(tokens);
    }
    else
    {
        tokens.shift();
        position++;
        return parse(tokens);
    }
}

var a = function(tokens)
{
    if (tokens[0] === 'A')
    {
        tokens.shift();
        aPosition = position;
        position++;
        return b(tokens);
    }
    else
    {
        return parse(tokens);
    }
}

var b = function(tokens)
{
    if (tokens[0] === 'B')
    {
        tokens.shift();
        position++;
        return c(tokens);
    }
    else
    {
        return parse(tokens);
    }
}

var c = function(tokens)
{
    if (tokens[0] === 'C')
    {
        tokens.shift();
        position++;
        count++;

        if (count === desiredCount)
        {
            return aPosition;
        }
        else
        {
            return parse(tokens);
        }
    }
    else
    {
        return parse(tokens);
    }
}