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notes from 2015

Javascript

is an object-oriented computer programming language commonly used to create interactive effects within web browers.

e.g.
document.write(“Hello from Javascript”);

Variable

is a storage location paired with an associated symbolic name (an identifier), which contains some known or unknown quatity of information referred to as a value.

is a stored piece of information (stored data) that can be changed.

Named Container for Storing Values
Can be set to anything
Declared using the var keyword

P.S.
must start your variable with letters or “_”
== is exact comparison
!== not the same
=== is strict comparison

// var myNumber = 42;

// document.write(myNumber);

// var myString = “This is a string392r23f*()))88”;

// document.write(myString);

// var myBool = false;

// document.write(myBool);

var myNumber = 42;

document.write(myNumber);

console.log(myNumber);

myNumber = myNumber + 10;

document.write(myNumber);

var myBool = 42 == 56

document.write(myBool);

var myVar

document.write(myVar);

var myExample = “42”;

document.write(myExample === 42);

// var paragraph = document.getElementById(“par2”).innerHTML;

// document.write(paragraph);

Datatype

is a piece of data with predefined characteristics.

Q: On what datatype in Javascript can calculations be done?
A: The “number” datatype. [p.s. integer does not exist in javascript]

Modifying HTML Content

Q: What property of the full mark up of an element is used to get its contents?
A: The “.innerHTML” property

document.getElementsByTagName(‘p’);
document.getElementById(‘par2’); from <p id=”par2″>paragragh2</p>

e.g.
document.getElementById(‘par2’).innerHTML = “Loading Amendments…”

Functions

Funtion
(or method) is a prewritten set of instructions that may or may not return a value.

Q: What keyword is used in Javascript to designate the creation of a function?
A: The “function” keyword.

Block of code designed to perform a particular task
Only runs when called
Declared using the function keyword

e.g.

// myFunc();

// myFunc();myFunc();myFunc();

// myFunc();

// function myFunc(){

// document.write(“myFunc() was called”)

// }

// myFunc();

// function myFunc(){

// document.getElementById(‘par2’).innerHTML = “This was changed by a function”;

// }

myFunc(“This is a dynamic argument!”);

function myFunc(input){

document.getElementById(‘par2’).innerHTML = input;

}

“Javascript Widgets”

• What is a Server?
• Web Hosting Services
• Introduction to XAMPP
• Putting Content Online

Programming Fundamentals
• Getting our web application to “think”
• Conditional logic, loops, and arrays

– Deductive Reasoning:

Q: If a card has a vowel on one side, it must have an even number on the other side

A. K. 2. 7.

A: Should be A and 7. (May be adding K as well, as you want to make sure the other side of K is not an even number.)

Which card(s) must be turned over to determine whether or not the rule has been followed?

Conditional Statement: is a if-then statement in which a hypothesis is followed by a conclusion.

The ‘if’ Statement

Found in every piece of software
Found in every web application
Simplest and most popular method to create conditional statements in programming

if (/*condition* */) {

//Execute this code

}

(L5 ppt)

Checks if the condition, or hypothesis, is met
Executes some code, or conclusion

The ‘else’ Statement

• Used at the end of an ‘if’statement

• Executes code when the ‘if’condition is not met

Array

Array is a special variable in Javascript (and other programming languages) that can hold multiple values at the same time.

var arrayName = [item1, item2, …];

From:

To:

Loop

Loop is a programming construct which allows one or more statements to be repeatedly executed a desired number of times.

For Loop

Executes a block of code a number of times.

for(statement 1; statement 2; statement 3){

// Code to be executed

}

eg:

for( i = 0; i < 5; i++) {

// Code to be executed

}

var animals = [‘cat’,’spider’,’dog’,’diraffe’,’elephant’,’whelk’,’parrot’,’peacocks’,’zebras’];

// document.write(animals[2].length);

// for( i = 0; i

for( i = 0; i

document.write(“====The for loop has executed=====

“);

document.write(“This is the “+i+”th run of the loop

“);

document.write(“The element in the animals array is ” +animals[i]+”

“)

}

Javascript Basics

Javascript

Variable

Datatype

Modifying HTML Content

Functions

Array

Loop

For Loop

While