Intro to Programming and JavaScript

What is Programming? Programming is the activity of creating a set of detailed instructions (Program) that when carried out on a consistent set of inputs will result in a consistent set of results. Programming has been around for several hundred years

History of Programming 1206 AD – Kurdish medieval scientist built a programmable automata – Used pegs and cams in different places that would trigger levers to produce a small drummer playing different rhythms and drum patterns. (Music Box) Jacquard Loom, pasteboard cards with holes punched in them which told the loom the pattern to weave the cloth

History of Programming 1830 – Charles Babbage adopted punch cards to control his Analytical Engine 1954 – FORTRAN is invented. Allowed user to enter in calculations by a formula directly (Y = X*2 + 5*X + 9) – Used a compiler to translate the text into machine language

History of Programming Late 1960’s – data storage and computer terminals were cheap enough that programs could be made directly on computers – Text editors could be used to program (Komodo) Popular programming languages: ActionScript, C++, C#, Haskell, HTML with PHP, Java, JavaScript, Objective-C, Perl, Python, Ruby, Smalltalk, SQL, Visual Basic, and dozens more.

Programming Lifecycle Requirements – Documenting the specifications of the problem Design – Creating the Algorithm to solve the problem Coding – Translating the Algorithm into instructions the computer can understand – Program Testing – Exercising the Program to ensure the expected results are achieved Debugging – If the expected results are not achieved; correcting the Algorithm or Program to address the “bugs” Retesting – Repeating all the testing to ensure the changes solved the problem(s) and didn’t create new problems Publishing – Making the Program available to the users

STOP Show programs

Algorithms and Pseudocode Algorithm – Detailed instructions for solving a problem Pseudocode – English like statements mixed with code statements for describing an algorithm

JavaScript Used mostly in web browsers Interaction with the user Control Alter content

Some JavaScript Examples html html

First JavaScript Command document.write(“Stuff goes in here.”); Needs to go in between document.write(“Stuff goes in here”); The above needs to go in the body.

First JavaScript Command cont. All JavaScript commands end with a semicolon You can put HTML into the JavaScript command: document.write(“ HTML from JavaScript ”);

Finding the Length of Words document.write(“This sentence has five e’s”.length); document.write(“Short word”.length); document.write(“Four”.length)

JavaScript Math! You can use JavaScript to do Math! document.write(3+4); document.write(3*4); document.write(3/4); Can write out a Math equation: document.write(“3+4=”, 3+4); Can multiply numbers with length of words: document.write(“Test”.length*10 );

JavaScript Communication You can talk to the user! confirm(“Today is a good day!”); confirm(“I am Batman”); You can ask for information: prompt(“What is your name?”); prompt(“What is your quest?”); prompt(“What is your favorite color?”);

JavaScript Data Types 1.Numbers: 3, 2.5, -1000, , etc. You can do math with them! 2.Strings: sequence of characters (words) in quotes “This is a string.” “Strings can also have numbers like 5 or symbols.”

JavaScript Data Types cont. Boolean: only take values true or false Statements can evaluate to true or false Examples: – 100 > 10 – 8 < 3 – 10.4 < 30 – “Test”.length < 2

JavaScript Comparisons > : Greater than < : Less than <= : Less than or equal to >= : Greater than or equal to === : Equal to !== : Not equal to

Practice Make these true: – document.write(20 10); – document.write(“John Smith”.length 100); – document.write(“USA” 3);

Conditionals Using Comparisons and Conditionals, computers can now make decisions if (100 > 2) { document.write(“That is correct!”); }

2 Decisions – If, else if (100 > 2) { document.write(“That is correct!”); } else { document.write(“That is incorrect.”); }

If and Else if (100 > 2) { document.write(“That is correct!”); } else { document.write(“That is incorrect.”); }

Any Type of Comparison in If/Else if (50/2 === “My Word”.length) { confirm(“Will the first block be displayed?”); } else { confirm(“Or the second block?”); }

Variables Variables are like “boxes” or “containers” that can hold data (strings, numbers, booleans) Declaring some variables: var varName = “String variable”; var myAge = 23; var myName = “Matt”; var myBool = true;

Some Variable Rules Variables can be letters and numbers: – No spaces or punctuation except underscores – When used, need to be spelled exactly Variables need to be declared once: var myVar = “Test variable”; myVar = “Changing test variable”;

Variables Can Save Data to be Used Later var test1 = confirm(“Yes or no?”); var test2 = prompt(“What is your favorite color?”); document.write(“You said: ”, test1, “ ”); document.write(“Your favorite color is: ”, test2, “ ”);

Using Conditionals, Variables, and User Input var myAge = prompt(“How old are you?”); if(myAge >= 18) { document.write(“Welcome to rated R movie.”); } else { document.write(“You cannot watch the rated R movie.”); }