Learn Js Nola - Functions

// Go to http://en.wikipedia.org/wiki/Alan_turing

// This is function syntax. Use a function to reuse code
// that you will use over and over again  paste this into
// the console
function changeHeader(toName) {
    $('h1').text(toName);
}

// Then this
changeHeader("George");

// Then this
changeHeader("Al Turing")


// Now refresh the page to clear everything out

// This is equivalent to the above function declaration but
// I prefer it since it is a lot clearer what is going on
// Which is that
var changeHeader = function(toName) {
    $('h1').text(toName);
};
// changeHeader is just an object like before
changeHeader.firstName = "George";
changeHeader['firstName'];
// but it has a special method
changeHeader.call(null, "George");
changeHeader.call(null, "Fred");
// This can be simpler written as
changeHeader("George");

// You can have many parameters in a function. And since
// an function is just an object you can pass in a function
var ifGeorge = function(name, doThis) {
   if(name == "George") {
      doThis.call(null, name);
   }
};
// or with the simpler syntax:
var ifGeorge2 = function(name, doThis) {
   if(name == "George") {
      doThis(name);
   }
};

// So you can call:
ifGeorge("Fred", changeHeader); //this will do nothing
ifGeorge("George", changeHeader); //this will change the header
var setParagraphs = function(newText) {
    $('p').text(newText);
};
ifGeorge("George", setParagraphs);
// or simply
ifGeorge("George", function(newText){
    $('p').text(newText);
});