JavaScript: Functional aspects of the language. Based on Christian Johansen's http://cjohansen.no/talks/2012/javazone/#/ talk.

functional_javascript.js

// A simple function
function add(a, b) {
  console.log(a + b);
}

// A first class function
// It can be passed along as a variable
var add = function (a, b) {
  console.log(a + b);
};

// A pure function:
// No side effects
var add = function (a, b) {
  return a + b;
};

// Higher-order functions
// A function can create and return another function
function makeAdder(base) {
  return function (num) {
    return base + num;
  };
}

var add2 = makeAdder(2);
add2(3); // 5
add2(7); // 9

var el = document.getElementById("btn");
el.addEventListener("click", function (event) {
    // ...
});

$("input[type=submit]").on("click", function (event) {
    // ...
});

// Loops,
// Why are we looping?
// Side-effects, transformation, filtering, combining, etc.

// Lets look at some alternatives
// Standard, focused on sequence
for (var i = 0, l = arr.length; i < l; ++i) {
    console.log(arr[i]);
}

// WHY are we looping? Not HOW are we looping...
arr.forEach(function (item) {
    console.log(item);
});

// What about mapping?
// From here:
var names = [];
for (var i = 0, l = tweeps.length; i < l; ++i) {
    names.push(tweeps[i].name);
}

// To here:
var names = tweeps.map(function (t) { return t.name; });