pset8: CS50 MacWilliam JavaScript pset8: CS50...

pset8: CS50Shuttle

TommyMacWilliam

JavaScript

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populate

pickup

dropoff

pset8: CS50 Shuttle

Tommy MacWilliam

[email protected]

November 6, 2011

pset8: CS50Shuttle

TommyMacWilliam

JavaScript

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populate

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Today’s Music

I Tommy’s ChoiceI Never Let Me Down (Kanye West)I Bulletproof (La Roux)I E.T. (Katy Perry ft. Kanye West)I Follow me Down (3OH!3)I Comedy Tragedy History (Akala)

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TommyMacWilliam

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Today

I JavaScript <333333333333333333333333333333I Distro codeI populate()I pickup()I dropoff()

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TommyMacWilliam

JavaScript

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JavaScript

I JavaScript is the best programming language everI other people will try to tell you otherwise

I they are wrong

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TommyMacWilliam

JavaScript

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JavaScript

I JavaScript is NOT JavaI Java is not the best programming language ever

I marketing ploy by Sun and OracleI the “hot new web-programming language”

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TommyMacWilliam

JavaScript

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JavaScript

I PHP: server-sideI runs on server, produces output, browser downloads

I JavaScript: client-sideI browser downloads, runs code

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TommyMacWilliam

JavaScript

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JavaScript

I syntax (also) very similar to C and PHPI if, else, for, while, etc.I strings are built in (just like PHP)I variables don’t need dollar signs (yay!)

I no types for variables or functionsI x = 5;I function increment(x) { return ++x; }

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TommyMacWilliam

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JavaScript

I insert into page using <script>I <script>alert("oh hi, mark!")</script>I <script src="file.js"></script>

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TommyMacWilliam

JavaScript

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JavaScript

I example time!I simple.html

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TommyMacWilliam

JavaScript

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Arrays

I lists created with the Array function

var a = Array(5);a[0] = 5;a[1] = "tommy";

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TommyMacWilliam

JavaScript

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Arrays

I can also be created with []I JavaScript arrays are dynamically-sized!

var b = [];b[3] = 3.14159;var c = [1, 2, 3, 4];

pset8: CS50Shuttle

TommyMacWilliam

JavaScript

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Associative Arrays

I just like PHP, JavaScript also has associative arrays(hashtables) built-in

var a = {};hash["key"] = "value";var tf = { name: "tommy", coolness: 100 };

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TommyMacWilliam

JavaScript

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Iterating

I for in can iterate over both array and associative array

var array = [1, 2, 3];for (var i in array)

alert(array[i]);

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TommyMacWilliam

JavaScript

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Objects

I associative arrays and objects (remember Stock?) arethe same

var tf = { name: "tommy", coolness: 100 };tf["name"] == "tommy"tf.coolness == 100

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TommyMacWilliam

JavaScript

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Objects

I members can also be functions

var tf = { name: "tommy", grade: function() { return "A"; }};tf.grade();

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TommyMacWilliam

JavaScript

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Arrays

I example time!I arrays.html

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TommyMacWilliam

JavaScript

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Scope

I in C, loops, conditions, and functions limit the scope ofvariables

I in JavaScript, only functions limit the scope of variables

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TommyMacWilliam

JavaScript

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Scope

I var creates a local variableI where local means to the current function only

I without var, variable is global

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TommyMacWilliam

JavaScript

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Scope

I example time!I scope.html

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TommyMacWilliam

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I buildings.js, houses.js: arrays containing objectsrepresenting buildings

I passengers.js: array containing objects representingstaff

I math3d.js: math, I’m no good at mathI shuttle.js: state of shuttleI service.js: functions for implementing shuttle serviceI index.html: brings it all together

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TommyMacWilliam

JavaScript

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Distro Code

I example time!

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TommyMacWilliam

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populate

I goal: remember location of each passengerI we need to know where they are to pick them up!

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TommyMacWilliam

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TODO

1. add passenger to passengers array

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TommyMacWilliam

JavaScript

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Arrays, again

I need to keep track of each passenger’s name, house,placemark, marker, etc.

I there are PASSENGERS.length total passengers in theworld

I sounds like a good size for an array

pset8: CS50Shuttle

TommyMacWilliam

JavaScript

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Objects, again

I when using for (var i in array), i is the currentindex in the array

I creating objects in JavaScript is easy!

var o = { key: "value" };var p = { something: o };

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TommyMacWilliam

JavaScript

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TODO

1. add passenger to passengers array

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TommyMacWilliam

JavaScript

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pickup

I goal: add passengers to the shuttleI also need to remove them from the worldI also need to remove them from the map

pset8: CS50Shuttle

TommyMacWilliam

JavaScript

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TODO

1. detect if in range2. add passenger to shuttle (if possible)3. remove placemark4. remove marker

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TommyMacWilliam

JavaScript

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Distance

I shuttle.distance(lat, lng) calculates distance fromcurrent position of shuttle to an arbitrary point

I lat: latitude of point to get distance toI lng: longitude of point to get distance to

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TommyMacWilliam

JavaScript

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Finding Passengers

I we already know where passengers are frompopulate()

I since we remembered a passenger’s placemark,marker, etc.

I need to check if we are near any passengerI loop through all passengers and calculate

shuttle.distance

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TommyMacWilliam

JavaScript

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Locating Passengers

I location information given by placemark associatedwith passenger

I from that placemark, need to getGeometry()associated with it

I from geometry, you can getLatitude() andgetLongitude()