HTML SSE

HTML5 Server-Sent Events

Server-Sent Events - One Way Messaging

A server-sent occasion is the point at which a web page naturally gets refreshes from a server.

This was likewise conceivable some time recently, however the web page would need to inquire as to whether any updates were accessible. With server-sent occasions, the updates come consequently.

Cases: Facebook/Twitter refreshes, stock value refreshes, news sustains, don comes about, and so forth.

Browser Support

Receive Server-Sent Event Notifications

Example

var source = new EventSource("demo_sse.php");
source.onmessage = function(event) {
    document.getElementById("result").innerHTML += event.data + "<br>";
}; 

Yourself Try

Check Server-Sent Events Support

In the tryit example above there were some extra lines of code to check browser support for server-sent events:

if(typeof(EventSource) !== "undefined") {
// Yes! Server-sent events support! // Some code..... } else {
// Sorry! No server-sent events support.. }

Server-Side Code Example

For the example above to work, you need a server capable of sending data updates (like PHP or ASP).
The server-side event stream syntax is simple. Set the "Content-Type" header to "text/event-stream". Now you can start sending event streams.
Code in PHP (demo_sse.php):

<?php
header('Content-Type: text/event-stream');
header('Cache-Control: no-cache');

$time = date('r');
echo "data: The server time is: {$time}\n\n";
flush();
?>

Code in ASP (VB) (demo_sse.asp):

<%
Response.ContentType = "text/event-stream"
Response.Expires = -1
Response.Write("data: The server time is: " & now())
Response.Flush()
%>

Wright © bestwebdesign and Graphics design

HTML Web Workers

HTML5 Web Workers

What is a Web Worker?

When executing contents in a HTML page, the page winds up plainly lethargic until the point that the content is done.

A web laborer is a JavaScript that keeps running out of sight, freely of different contents, without influencing the execution of the page. You can keep on doing whatever you need: clicking, choosing things, and so on., while the web specialist keeps running out of sight.

Browser Support

Check Web Worker Support

Before making a web laborer, check whether the client's program underpins it:

if (typeof(Worker) !== "undefined") {

    // Yes! Web worker support!
    // Some code.....
 }
 else {

    // Sorry! No Web Worker support..
 }

Create a Web Worker File

var i = 0;

function timedCount()
{

i = i + 1;

postMessage(i);

setTimeout("timedCount()",500);

}

timedCount();

Create a Web Worker Object

if (typeof(w) == "undefined") {
w = new Worker("demo_workers.js");
}

Then we can send and receive messages from the web worker.
Add an "onmessage" event listener to the web worker.

w.onmessage = function(event){
document.getElementById("result").innerHTML = event.data;
};

Terminate a Web Worker

When a web worker object is created, it will continue to listen for messages (even after the external script is finished) until it is terminated.
To terminate a web worker, and free browser/computer resources, use the terminate() method:

w.terminate();

Reuse the Web Worker

w = undefined;

Full Web Worker Example Code

Example

<!DOCTYPE html>

<html>

<body>

<p>Count numbers: <output id="result"></output></p>

<button onclick="startWorker()">Start Worker</button> 

<button onclick="stopWorker()">Stop Worker</button>

<script>

var w;

function startWorker()
{

if(typeof(Worker) !== "undefined")
{

        if(typeof(w) == "undefined") {

            w = new Worker("demo_workers.js");

        }

        w.onmessage = function(event) {

            document.getElementById("result").innerHTML = event.data;

        };

}
else
{

document.getElementById("result").innerHTML = "Sorry! No Web Worker support.";
   
}

}

function stopWorker()
{ 

w.terminate();
    w = undefined;

}

</script>

</body>

</html>

Yourself Try

Wright © bestwebdesign and Graphics design

HTML Web Storage

desing20:52Html, HTML APIs No comments:

HTML5 Web Storage

What is HTML Web Storage?(Wright-bestwebdesign)

With web storage, web applications can store data locally inside the customer's program.

Before HTML5, application data must be secured in treats, consolidated into every server request. Web storage is more secure, and a considerable measure of data can be secured locally, without affecting website execution.
Not in the slightest degree like treats, quite far will be far greater (no under 5MB) and information is never traded to the server.
Web storage is per beginning stage (per space and tradition). All pages, from one beginning stage, can store and access comparative data

Browser Support

The localStorage Object

Example

// StorelocalStorage.setItem("lastname", "Smith");
// Retrieve
 document.getElementById("result").innerHTML = localStorage.getItem("lastname");

Yourself Try

The sessionStorage Object

Example

if (sessionStorage.clickcount) {
    
sessionStorage.clickcount = Number(sessionStorage.clickcount) + 1;
}
else {
    sessionStorage.clickcount = 1;
}

document.getElementById("result").innerHTML = "You have clicked the button " +

sessionStorage.clickcount + " time(s) in this session.";

Yourself Try

Wright © bestwebdesign and Graphics design

HTML Drag and Drop

desing20:42Html, HTML APIs No comments:

HTML5 Drag and Drop

Drag and Drop

Drag and drop is an exceptionally basic element. It is the point at which you "get" a protest and drag it to an alternate area.
In HTML5, drag and drop is a piece of the standard: Any element can be draggable.

HTML Drag and Drop Example

Example

<!DOCTYPE HTML>

<html>

<head>

<script>

 function allowDrop(ev)
 {

 ev.preventDefault();

 }

 function drag(ev)
 {

 ev.dataTransfer.setData("text", ev.target.id);

 }

 function drop(ev)
 {

 ev.preventDefault();

 var data = ev.dataTransfer.getData("text");

 ev.target.appendChild(document.getElementById(data));

 }

 </script>

</head>

<body>

<div id="div1" ondrop="drop(event)"
 ondragover="allowDrop(event)"></div>

<img id="drag1" src="img_logo.gif" draggable="true"

 ondragstart="drag(event)" width="336" height="69">

</body>

</html>

Yourself Try

HTML Geolocation

desing20:28Html, HTML APIs No comments:

HTML5 Geolocation

Using HTML Geolocatio

The getCurrentPosition() technique is utilized to restore the client's position.

The case underneath restores the scope and longitude of the client's position:

Example

 <script>
var x = document.getElementById("demo");
function getLocation() {
    if (navigator.geolocation) {
        navigator.geolocation.getCurrentPosition(showPosition);
    } else {
        x.innerHTML = "Geolocation is not supported by this browser.";
    }
}

 function showPosition(position) {
    x.innerHTML = "Latitude: " + position.coords.latitude + 
    "<br>Longitude: " + position.coords.longitude; 

 }</script> 

Yourself Try

Handling Errors and Rejections

Example

function showError(error) {
    switch(error.code) {
        case error.PERMISSION_DENIED:
            x.innerHTML = "User denied the request for Geolocation."
            break;
        case error.POSITION_UNAVAILABLE:
            x.innerHTML = "Location information is unavailable."
            break;
        case error.TIMEOUT:
            x.innerHTML = "The request to get user location timed out."
            break;
        case error.UNKNOWN_ERROR:
            x.innerHTML = "An unknown error occurred."
            break;
    }

 } 

Yourself Try

Displaying the Result in a Map

Example

function showPosition(position) {
    var latlon = position.coords.latitude + "," + position.coords.longitude;

    var img_url = "https://maps.googleapis.com/maps/api/staticmap?center=

     "+latlon+"&zoom=14&size=400x300&sensor=false&key=YOUR_:KEY";

 document.getElementById("mapholder").innerHTML = "<img src='"+img_url+"'>";

 }

Yourself Try

Freelancign web design and Graphics design

Tuesday, 5 December 2017

HTML5 Server-Sent Events

Server-Sent Events - One Way Messaging

Browser Support

Receive Server-Sent Event Notifications

Example

Check Server-Sent Events Support

Server-Side Code Example

Wright © bestwebdesign and Graphics design

HTML5 Web Workers

What is a Web Worker?

Browser Support

Check Web Worker Support

Before making a web laborer, check whether the client's program underpins it:

Create a Web Worker File

Create a Web Worker Object

Terminate a Web Worker

Reuse the Web Worker

Full Web Worker Example Code

Example

HTML5 Web Storage

What is HTML Web Storage?(Wright-bestwebdesign)

Browser Support

The localStorage Object

Example

The sessionStorage Object

Example

HTML5 Drag and Drop

Drag and Drop

Drag and drop is an exceptionally basic element. It is the point at which you "get" a protest and drag it to an alternate area. In HTML5, drag and drop is a piece of the standard: Any element can be draggable.

HTML Drag and Drop Example

Example

HTML5 Geolocation

Using HTML Geolocatio

The getCurrentPosition() technique is utilized to restore the client's position. The case underneath restores the scope and longitude of the client's position:

Example

Handling Errors and Rejections

Example

Displaying the Result in a Map

Example

Wright © bestwebdesign and Graphics design

Pages

Labels

Blog Archive

Recent Posts

Web Design Tutorial

Theme Support

Drag and drop is an exceptionally basic element. It is the point at which you "get" a protest and drag it to an alternate area.
In HTML5, drag and drop is a piece of the standard: Any element can be draggable.

The getCurrentPosition() technique is utilized to restore the client's position.

The case underneath restores the scope and longitude of the client's position: