JavaScript cheat sheet

cheat.js

// Fantastic guide: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Grammar_and_types

// ------------------ literals ----------------------
var integer = 7;
var float = 7.7;
var str1 = "Hello world!";
var str2 = 'Hello world!';
var object = {};
var array = ["a", "b"];

// ------------------ functions ------------------

// Named function
function add(a,b) {
    return a + b;
}

// Anonymous function
var multiply = function(a,b) {
    return a * b;
}

// Anonymous function passed as a parameter to another function
window.requestAnimationFrame(function (timestamp) {
   console.log("Anonymous function called! " + timestamp); 
});

// Named function passed as a parameter to another function
function render(timestamp) {
   console.log("Anonymous function called! " + timestamp); 
}
window.requestAnimationFrame(render);

// Anonymous function copied onto "onload" property of image object 
var img = new Image();
img.onload = function(event) {
    console.log(event);
}
img.src = "http://www.drodd.com/images12/happy-face15.jpg";

// ------------------ objects -----------------------

// Empty object literal
var empty = {};

// Object literal with properties
var person = {
    firstName: "Brent",
    lastName: "Gardner"
};

// Build object (equivalent to above literal)
var person = new Object();
person.firstName = "Brent";
person.lastName = "Gardner";

// Object propery accessors (equivalent to above literal)
var person = new Object();
person["firstName"] = "Brent";
person["lastName"] = "Gardner";

// ------------------- iteration ---------------------

// Iterate by 1
for(var i = 0; i < 10; i++) {
    console.log(i);
}

// While loop iterate by 1 (equivalent to above)
var i = 0;
while(i < 10) {
    console.log(i++);
}

// Iterate over array
var ar = ["a", "b", "c"];
for(var i = 0; i < ar.length; i++) {
    var item = ar[i];
    console.log(item);
}

// Iterate over keys in an object
var person = {
    firstName: "Brent",
    lastName: "Gardner"
};
for(var key : person) {
    var value = person[key];
    console.log(key + "=" + value); // output: firstName="Brent" lastName="Gardner"
}