<select name="cars" id="cars" multiple>
  <option value="volvo1">Volvo1</option>
  <optgroup label="Swedish Cars">
    <option value="volvo">Volvo</option>
    <option value="saab">Saab</option>
  </optgroup>
  <optgroup label="German Cars">
    <option value="mercedes">Mercedes</option>
    <option value="audi">Audi</option>
  </optgroup>
</select>

<optgroup>

is used to group several options together

<header>

- defines a header for a document or section;

<nav>

- defines a set of navigation links;

<main>

- specifies the main content of a document;

<footer>

- defines a footer for a document or section;

<article>

- defines an article;

<section>

- defines a section in a document;

<aside>

- defines content aside from the page content;

We can use a function instead of an array as the

replacer

let room = {
  number: 23
};

let meetup = {
  title: "Conference",
  participants: [{name: "John"}, {name: "Alice"}],
  place: room // meetup references room
};

room.occupiedBy = meetup; // room references meetup

// All the properties (except occupiedBy) are the encoded
document.write( JSON.stringify(meetup, function replacer(key, value) {
  return (key == 'occupiedBy') ? undefined : value;
}));

The function will be called for every

(key, value)

pair and should return the

replaced

value, which will be used instead of the original one. Or

undefined

if the value is to be skipped. ... In our case, we can return

value

“as is” for everything except

occupiedBy

. To ignore

occupiedBy

, the code above returns

undefined

. The result of the code above will be the following:

{"title":"Conference","participants":[{"name":"John"},{"name":"Alice"}],"place":{"number":23}}

As we expected all the values are encoded except

occupiedBy

JSON schema

is a JSON document that describes other JSON document. It is a specification for JSON based format to define the structure of JSON data

- Describes your existing data format
- Defines the structure of a JSON message
- Clear, human- and machine-readable documentation
- Complete structural validation, useful for automated testing
- Complete structural validation, validating JSON message
- Can be used to validate API request and response

Let's first create

parent

and

grandparent

clases

class A {
    public static function who() {
        echo __CLASS__;
    }
}

class B extends A {
    public static function who() {
        parent::who();
    }
}

One way to call grandparent's

who

method is to use the grandparent class name

A

class C extends B {
    public static function who() {
        A::who();
    }
}

C::who();

Another way is to call

who

method of parent class which also calls its parent class (which is grandparent for

C

class)

class C extends B {
    public static function who() {
        parent::who();
    }
}

C::who();

Makes controller for

Posts

php artisan make:controller PostsController

With the following basic content

<?php

namespace App\Http\Controllers;

use Illuminate\Http\Request;

class Postscontroller extends Controller
{
    //
}

Creates controller and empty methods in it (with appropriate comments)

php artisan make:controller PostsController --resource

The methods are:

index()

- Displays a list of the resource.

create()

- Shows the form for creating a new resource

store(Request $request)

- Stores a newly created resource in storage

show($id)

- Displays the specified resource

edit($id)

- Shows the form for editing the specified resource

update(Request $request, $id)

- Updates the specified resource in storage

destroy($id)

- Removes the specified resource from storage

We can use

first-child

to select only the first child element:

.my-list li:first-child {
    background-color: red;
}

last-child

is used to select the last member from the list:

my-list li:last-child {
    background-color: blue;
}

nth-child(5)

is used to select

nth

element. In the example we select 5th element

.my-list li:nth-child(5) {
    background-color: yellow;
}

We can also use

nth-child(even)

to select even members from the list

.my-list li:nth-child(even) {
    background-color: grey;
}

We can print some text before every paragraph as well as after every paragraph

p:before { 
    color: red; 
    content: "read this carefully"; 
}
p:after { 
    color: red; 
    content: "you have read it! good job"; 
}

XML Processing instructions allow documents to contain instructions for applications. PI consists of two parts: 1.

target

- Identifies the application to which the instruction is directed. 2.

instruction

- A character that describes the information for the

target

application to process. ... PI's example in real XML document

<?xml version="1.0" encoding="UTF-8"?>
<student>
    <?sort alpha-ascending?>
    <?textinfo whitespace is allowed ?>
    <first-name>George</first-name>
    <phone.mobile>(011) 123-4567</phone.mobile>
</student>

In this example we have two PIs 1.

sort

with value -

alpha-ascending

2.

textinfo

with value -

whitespace is allowed

... Note: processing instructions can contain any data except the combination

?>

, which is interpreted as a closing delimiter

IF

has three parameters: 1 - Condition. 2 - Executes if the condition evaluates to

true

3 - Executes if the condition evaluates to

false

IF(condition , [expression when true], [expression when false]);

Returns

false

because the first parameter

0

evaluates to false

SELECT IF(0, 'true', 'false') AS Boolean

Simple

IF

statement in

SELECT

clause

SELECT *, 
    IF(points>=90, "Brilliant", "Lazy") AS class
FROM `students`
ORDER BY points DESC

Nested IF

conditional statement. Categorizes students based on their points

SELECT *, 
    IF(points>=90, "Brilliant", IF(points>=80, "Gold", IF(points>=60, "Silver", "Lazy"))) AS class
FROM `students`
ORDER BY points DESC

Sub-query inside

IF

. Highlights the student with highest points

SELECT *, 
    IF(points>=90, IF(points=(SELECT MAX(points) FROM students), "Highest", "Brilliant"), IF(points>=80, "Gold", IF(points>=60, "Silver", "Lazy"))) AS class
FROM `students`
ORDER BY points DESC

IF

statement in

WHERE

clause. Checks

mail

if it is not empty otherwise checks

mail2

SELECT * 
FROM `students` 
WHERE IF(LENGTH(mail), mail, mail2) LIKE '%gmail.com%'