Reverse Camel Case implementation

camel_case_rev.js

function camel_case_rev(word)
{
        if(! word)
                return;

        word = (word).toString();

        var ret = "";

        for(var i = 0; i < word.length; i++)
        {
                if(word[i] <= 'Z' && word[i] >= 'A')
                {
                        ret += String.prototype.toLowerCase.call(word[i]);
                }
                else if(word[i] <= 'z' && word[i] >= 'a')
                {

                        ret += String.prototype.toUpperCase.call(word[i]);
                }
                // non alpha
                else
                {
                        ret += word[i];
                }

        }

        return ret;

}


prog = process.argv[1];

if(process.argv.length < 3) {
        console.log("USAGE: " + prog + " <string>");
        process.exit();
}

console.log(camel_case_rev(process.argv[2]));