Learning JavaScript

gistfile1.txt

// Most of this was taken from this awesome blog post: https://www.discovermeteor.com/blog/javascript-for-meteor/?utm_content=bufferf9e86&utm_medium=social&utm_source=twitter.com&utm_campaign=buffer

// If you happen to the be the author of this blog post and you don't like how I just scaped it and put all of this code in this Gist then please feel free to email me at swaters86@gmail.com and let me know that I should take it down. 

// Other sources:
// https://developer.mozilla.org/en-US/docs/Web/JavaScript
// http://addyosmani.com/resources/essentialjsdesignpatterns/book/#prototypepatternjavascript

// How to declare a variable
var a;

// How to declare a LOCAL variable and assign a value to it
// Will restrict it's scopt to the function you're declaring it in
var a = 12;

// How to declare a GLOBAL variable and assign a value to it
// Will make it avaiable to your whole script, try to avoid this so you don't pollute the global    scope 

a = 12;

// How to declare a function in JavaScript
var myAwesomeFunction = function ( myArgument ) {
    myAwesomeFunction( something );
}

// Using functions as arguments for other functions

// Declare the function to be used as an argument
square = function ( a ) {
    return a * a;
}

// Declare the applyOperation function
applyOperation = function ( f, a ) {
    return f( a );
}

// Alert the return value of the 'applyOperation' function when the 'square' function is used as an argument
applyOperation(square, 10) // returns 100 

// The return statment returns the result of the function , anything after the return statement will not get executed 
myFunction = function ( a ) {
    return a * 3;
    explodeComputer(); // will never get executed (hopefully!)
}

// If statement in JavaScript 
if ( foo ) {
    return bar;
}

// Shorthand verison of the If statment. This Works as long as the block of code inside the if statment can fit on 1 line. 
if ( foo ) return bar;

// If / Else statemenst in JavaScript 
if ( foo ) {
    function1();
} else {
    function2();
}

// If / Else statments have their own shorthand syntax 
foo ? function1() : function2();

// This is particularly useful when assinging a value to a variable 
var n = foo ? 1 : 2;

// If / Else statment with another If / Else statment 
if ( foo ) {
    function1();
} else if ( bar ) {
    function2();
} else {
    function3();
}

// How to define an array in JavaScript 
var a = [ 123, 456, 789 ];

// How to access an items in the above array 
a[1]; // 456

// How to define an object in JavaScript 
myProfile = {
    name: "John Smith",
    email: "johnsmith@gmail.com",
        'zip code': 12345,
    isInvited: true
}

// You can nest objects and even use arrays in JavaScript objects
myProfile = {
    name: "John Smith",
    email: "johnsmith@gmail.com",
    city: "San Francisco",
    points: 1234,
    isInvited: true,
    friends: [{
        name: "John Doe",
        email: "johndoe@gmail.com"
    }, {
        name: "Jane Doe",
        email: "janedoe@gmail.com"
    }]
}

// Accessing an object's property (using dot notation with array syntax)
myProfile.name; // John Smith
myProfile.friends[1].name; // Jane Doe

// Instead of defining 'square' function and passing it as an argument, we are defining it inside of the argumetn call
applyOperation = function ( f, a ) {
    return f( a );
}
applyOperation(
// Defining 'square' function
function ( a ) {
    return a * a;
},
10) // 100

// Pushing new items to an array 
var myArray = [ 123, 456 ];
myArray.push( 789 ) // 123, 456, 789

// String replacements 
var myString = "abcdef";
myString.replace("a", "z"); // "zbcdef"

// Changing functions in JavaScript using the 'something.function1().function2().function3()' pattern
n = 5;
n.double().square(); //100

// Assignment operators 

// Assinging a value to a variable
a = "12";

// Comparing a to 12 
a == 12; // true

// Comparing both value and type
// a is a string value , while 12 is not an integer so false is returned
a === 12; // false

// Inequality Operator
a = 12;
a !== 11; // true

// Getting the opposite of a boolean value using the ! inequality operator 
a = true;
!a; // false

// A boolean value is always returned even if the varaible you're chekcing against isn't a boolean value 
a = 12;
!a; // false

// Converting a variable by using the ! inequality operator twice (once to force the variable to boolean, a second time to revert the value back)
a = 12; !! a; // true

// Or
a = 0; !! a; // false

// How to set a timeout for executing a function in 5 seconds
window.setTimeout(function() {
    alert( "Hello World!" );
}, 500);

// How to cancel a timeout before it executes a function
var timeoutID;

timeoutID = window.setTimeout(function() {
    alert( "Hello World!" );
}, 500);

window.clearTimeout(timeoutID);

// How to create a prototype 
var myCar = {
 
  name: "Ford Escort",
 
  drive: function () {
    console.log( "Weeee. I'm driving!" );
  },
 
  panic: function () {
    console.log( "Wait. How do you stop this thing?" );
  }
 
};
 
// Use Object.create to instantiate a new car
var yourCar = Object.create( myCar );
 
// Now we can see that one is a prototype of the other
console.log( yourCar.name );