reading-notes

This Repo required for Asac labs class 2

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JavaScript

Chapter 2: “Basic JavaScript Instructions”

STATEMENTS:

What is a script ?

A script is a series of instructions that a computer can follow one-by-one.

What is a Statement ?

statement is each individual instruction or step of the script, Statements should end with a semicolon.

what are code blocks?

the curly braces that Some statements are surrounded by. The closing curlybrace is not followed by a semicolon.

What is a VARIABLE?

A script will have to temporarily store the bits of information it needs to do its job. It can store this data in variables. in a variable can change (or vary) each time a script runs. structure:

variable-key variable-name;

assign a value to the variable:r

variable-name = variable-value;

DATA TYPES:

• NUMERIC DATA TYPE

  • The numeric data type handles, an integer or a floating-point number. numbers.
• STRING DATA TYPE
  • The strings data type consists of letters and other characters.
• BOOLEAN DATA TYPE
  • Boolean data types can have one of two values: true or false.

CHANGING THE VALUE OF A VARIABLE :

variable-name = variable-value;

RULES FOR NAMING VARIABLES

1. The name must begin with a letter,($),or(_).It must not start with a number.

2. you must not use (-) or (.) in a variable name.

3. All variables are case sensitive.

4. Use a name that describes the kind of information that the variable stores.

5. You cannot use keywords or reserved words.

6. If your variable name is made up of more than one word, use a capital letter for the first letter of every word after the first word.

ARRAYS

what is an array ?

An array is a special type of variable. It doesn’t just store one value; it stores a list of values. you can use it on a list or a set of values that are related to each other.

How to create an (literal)Array?

var Array-Name = [value1,value2…valueN]

How to create an Array with n array constructor?

var Array-Name = new Array(value1 , value2,valueN);

Note

The array literal is preferred over the array constructor when creating arrays.

VALUES IN ARRAYS

Values in an array are accessed as if they are in a numbered list. It is important to know that the numbering of this list starts at zero (not one).

ACCESSING & CHANGING VALUES IN AN ARRAY

Update the an item in the array: colors[the-item’s-index-number] = NewValue ;

EXPRESSIONS

what is an expression?

An expression evaluates into (results in) a single value.

types of expressions:

1. EXPRESSIONS THAT JUST ASSIGN A VALUE TO A VARIABLE

   var variable-name = variable-value;

2. EXPRESSIONS THAT USE TWO OR MORE VALUES TO RETURN A SINGLE VALUE

   var variable-name = value1 (* - + % / ) value2

OPERATORS

Expressions rely on things called operators; they allow programmers to create a single value from one or more values.

Operators’ Types:

1. ARITHMETIC OPERATORS

   • JavaScript contains the following mathematical operators, which you can use with numbers. You may remember some from math class.

\

1. STRING OPERATOR
   • There is just one string operator: the+ symbol. It is used to join the strings on either side of it.

   • two operators are used in string operators:

     • = (normal operator sign a value)
     • += (concatenation operator combine old and new values)

Sammary:

• A script is made up of a series of statements. Each statement is like a step in a recipe.
• Scripts contain very precise instructions. For example, you might specify that a value must be remembered before creating a calculation using that value.
• Variables are used to temporarily store pieces of information used in the script.
• Arrays are special types of variables that store more than one piece of related information.
• JavaScript distinguishes between numbers (0-9), strings (text), and Boolean values (true or false).
• Expressions evaluate into a single value.
• Expressions rely on operators to calculate a value.

Chapter 4: “DECISIONS & LOOPS”

Using a flowchart will help making decisions

Evaluating a Condition and Conditional Statment

components of decision:

1. EVALUATION OF A CONDITION: An expression is evaluated, which returns a value

2. CONDITIONAL STATEMENTS: A conditional statement says what to do in a given situation

### USING COMPARISON OPERATORS:

var var1 = value1;
var var2 = vakue2;
var Comparison-variable = var1 (>,<,>=,<=,==,===,!=,!==) var2;

Logical Operatrs:

Logical operators are used to determine the logic between variables or values.

• && -> Logical and

• -> Logical or

• ! -> Logical not

If Statement:

The if statement evaluates (or checks) a condition. If the condition evaluates to true, any statements in the subsequent code block are executed.

IF…ELSE STATEMENTS

The if…else statement checks a condition. If it resolves to true the first code block is executed. If the condiion resolves to false the second code block is run instead.

…………………………………………………………………………………………………………………………………………………………………….

HTML

Chapter 2: “Text”

Headings:

<h1> <h2> <h3> <h4> <h5> <h6>

• H1 is the biggest and h6 is the smallest.

• the diffrence between headings is the level of important

  • i.e. h1 for the main headings and subheadings for the subheadings

Paragraphs: <p>

• To create a paragraph

  <p>the paragraph you want</p>

Bold & Italic

bold:<b>

<b>This is bold text</b>

The Result: This is bold text

Italic:<i>

<i>This is Italic text</i>

The Result: This is Italic text

Superscript: <sup>

value^th

The Result: value^th

Subscript: <sub>

value_th

The Result: value_th

White Space:

white space collapsing: When the browser comes across two or more spaces next to each other, it only displays one space.

<p>Some                         text</p>

The Result: <p>Some text</p>

Line Breaks:<br>

Some<br>text

The Result:

Some
text

Horizontal Rules: <hr>

some <hr>text

The Result:

some <hr>text

Semantic Markup:

Semantic Markup: elements that are not intended to affect the structure of your web pages, but they do add extra information to the pages — they are known as semantic markup. i.e. <em><blockquote>

Strong:<strong>

<strong>strong text</strong>

The Result: strong text

Emphasis:<em>

The <em> element indicates emphasis that subtly changes the meaning of a sentence. By default browsers will show the contents of an <em> element in italic.

text <em>Emphasis</em> text

The Result: text Emphasis text

Quotations:<blockquote><q>

<blockquote>:

The <blockquote> element is used for longer quotes that take up an entire paragraph. Browsers tend to indent the contents of the <blockquote>

<blockquote> element is used for longer quotes that take up an entire paragraph. Browsers tend to indent the contents of the </blockquote>

The Result:

element is used for longer quotes that take up an entire paragraph. Browsers tend to indent the contents of the

<q>:

The <q> element is used for shorter quotes

<q>This element is used for shorter quotes </p>

The Result:

This element is used for shorter quotes </p>

Abbreviations & Acronyms:<abbr>

<abbr title=”Professor”>Prof</abbr>

The Result:

Prof

Citations:<cite>

When you are referencing a piece of work such as a book, film or research paper, the text will be italic

<cite>a work name</cite> by auther

The Result: a work name by auther

Definitions:<dfn>

The <dfn> element is used to indicate the defining instance of a new term.the text will be italic

A <dfn>black hole</dfn>

The Result: A black hole

Author Details:<address>

<address> <a href=”mailto:homer@example.org”> \homer@example.org</a>

<p>742 Evergreen Terrace, Springfield.</p> </address>

The Result:

homer@example.org

742 Evergreen Terrace, Springfield.

Changes to Content: <ins><del><s>

It was the <del>worst</del> <ins>best</ins> idea <s>Was $995</s>

The Result:

It was the worst best idea Was $995

Summary

Text

• HTML elements are used to describe the structure of the page (e.g. headings, subheadings, paragraphs).
• They also provide semantic information (e.g. where emphasis should be placed, the definition of any acronyms used, when given text is a quotation)

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Chapter : “Introducing CSS”

CSS allows you to create rules that control the way that each individual element (and the contents of that element) is presented.

selector:

indicate which element the rule applies to.

declaration:

indicate how the elements referred to in the selector should be styled.

• parts od declaration:
  • property: indicate the aspects of the element you want to change
  • value: specify the settings you want to use for the chosen properties

Summary

INTRODUCING CSS

• CSS treats each HTML element as if it appears inside its own box and uses rules to indicate how that element should look.
• Rules are made up of selectors (that specify the elements the rule applies to) and declarations (that indicate what these elements should look like).
• Different types of selectors allow you to target your rules at different elements.
• Declarations are made up of two parts: the properties of the element that you want to change, and the values of those properties. For example, the font-family property sets the choice of font, and the value arial specifies Arial as the preferred typeface.
• CSS rules usually appear in a separate document, although they may appear within an HTML page.