Section 1
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Multi Paradigm Language
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Date created
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Section 1
(50 cards)
Multi Paradigm Language
Supports more than one programming paradigm - developers can work with a variety of styles within javascript.
What are the 2 types of Numbers within Datatypes?
Integer: Whole Number (-1, 450) Float:Decimal Point (0.1, 12.454)
How do you add JS to your site externally?
Add by externally linking to .js files.
Comparison Operators
First Class Function
Treats functions as first class citizens - you can do with functions everything you can do with other elements.
The alert() function is not much used in JavaScript. What is it is useful for?
It is often quite handy for trying out code.
What kind of value does Boolean take?
True or False
Do While Loop
Iterate while the condition is true do { ... this thing } while(condition);
What type of language is JavaScript?
It is a scripting language.
What is best practice regarding variable declarations?
Put variable declarations as close to the top of the scope as possible.
How do you declare variables?
using the var keyword - eg. var myName="Monica";
Is JS case sensitive?
Yes
What are the properties of Global Scope?
Outside a function, available to any code outside that function (also within).
JS Statement
A command that tells the browser what to do. document.write("hello world"); var myName="lorna";
What would be the result of the following code? <script> document.write("<h1>This is a heading</h1>"); document.write("<p>This is a paragraph</p>"); </script>
It will write what is between the <h1> and <p> tags to the browser screen formatted accordingly to the respective HTML tags
Loops
Repetitive Conditional statements. Used to perform a calculation a number of times, or to iterate over a set of variables.
Are variables case sensitive?
Yes
How do you add JS To your site internally?
Internally using html <script></script> tag. Best practice to place it before closing body tag .
console.log(THING_TO_OUTPUT)
A built-in JavaScript function that will push messages to the browsers error console. It is a very useful tool for debugging code, for seeing how variables are changing in your code. You can output strings, numbers, variables, objects, arrays and combinations of these for inspection.
Objects
Custom datatypes with properties and actions
Math.random()
Generates a random floating point number between 0 & 1. To convert this to a number range that we want - for example a random number between 1 & 10. First we multiply the result of Math.random() by 10 (the amount of potential numbers from 1 to 10) - this will give us numbers that range from 0 to 9.99999. Because Math.random() won't ever return the whole number 1 and to remove the decimal places, we use Math.ceil()to round the result of Math.random()*10 up to the nearest whole number. See more on the Math object.
What are Strings within Datatypes?
A line of text: "frog", "a red truck"
What must a variable begin with?
A letter, $ or _
Function
Re-useable blocks of instructions that can be executed by name. -Perform common tasks -saves time, reduces error function functionName (data) { repeat action here return outcome }
Operators
Used to assign values to variables and perform mathematical operations on them
What are the properties of a Local Scope?
Within a function, only available within function
DOM
Document Object model.
Example of Conditional ELSE Statement
Else statements allow us to make an alternative statement if original condition is false if (this condition is true){ ...do this thing }else{ ...do this other thing }
Example of comparison operators
var num = "5"; var numString ="5", ==Interpreted Value num ==numString (true) ===Interpreted value and data type num===numString(false)
Can a statement be grouped into useable blocks called functions?
Yes.
What is DOM?
Representation of HTML Page....
Datatypes
Numbers, Strings, Boolean, Arrays, Objects.
What will an undeclared variable return?
Undefined
Conditionals
Statements that allow for code to be executed against conditionals IF, ELSE statements
Prototype Based
Each object has a prototype that it inherits properties and abilities from
For Loop Example
Repeats until a specific condition becomes false
Math Based Operators
Dynamic Typing
Dynamic if the type of variable is interpreted at runtime.
Three main types of Loops
For: Set Number of Iterations While: Certain conditions are met Do...While: Certain condition is met
Two types of variable scope?
Local and Global
What is a scripting language?
A scripting language is a lightweight programming language.
What will this code do? <p id="demo"> JavaScript can change the content of an HTML element.</p> <script> function myFunction() { x=document.getElementById("demo"); // Find the element x.innerHTML="Hello JavaScript!"; // Change the content } </script>
It will change the text between the <p> tags to the content in quotes after x.innerHTML Hello JavaScript!
What is a variable?
Container for a piece of data
What are the two ways to add JS to your site?
Internally and Externally.
What is Variable "Hoisting"?
Variables are hoisted to the top of the function/statement. It is useful because you can refer to variables declared later in the code.
While Loop Example
Iterate while the condition is true while (condition) { do this thing }
What happens if you call the "document.write" function after the document has fully loaded?
The html document will be deleted and replaced by your new content.
Function Example
function sayHello(){ alert ("hello everyone!"); }
Example of Conditional IF Statement
if (This condition is true) {Do this thing} var Country = "Australia"; var Hemisphere, var Language; if (country = "England") { hemisphere = "northern"; language = "english"; }
What is an Array?
Used to store multiple values in a single variable. Real ["blue", "5", "123456"] Refer to the whole array using its variable name Arrays are indexed from 0
Section 2
(30 cards)