http://toys.usvsth3m.com/javascript-under-pressure/

gistfile1.js

function doubleInteger(i) {
    
    // i will be an integer. Double it and return it.
    
    
    
    return i + i;
    
}

function isNumberEven(i) {
    
    // i will be an integer. Return true if it's even, and false if it isn't.
    
    return !(i % 2)
    
    
}

function getFileExtension(i) {
    
    // i will be a string, but it may not have a file extension.
    // return the file extension (with no period) if it has one, otherwise false
    
    var index = i.indexOf('.');
    return index > -1 ? i.slice(index+1) : false;
    
}

function longestString(i) {
    
    // i will be an array.
    // return the longest string in the array
    
    return i.reduce(function (ret, item) {
        if (!item.toUpperCase) {
            return ret;
        }
        return ret.length > item.length ? ret : item;
    })
    
}

function arraySum(i) {
    
    // i will be an array, containing integers, strings and/or arrays like itself.
    // Sum all the integers you find, anywhere in the nest of arrays.
    
    return i.reduce(function (ret, item) {
        if (Array.isArray(item)) {
            return ret + arraySum(item);
        }
        return item.toFixed ? ret + item : ret;
    }, 0)
    
}