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Node.js Free Video Tutorials

progress Element: HTML5

Lets look at the progress element of HTML5.

You could implement this progress element of HTML5 with the file upload or the user form filling etc, to indicate the amount of upload or the profile completion.

HTML file
index.html

< !DOCTYPE html>
<html>
<head>
<title>progress Element: HTML5</title>
<link href="myStyle.css" rel="stylesheet"/>
</head>
<body>
 
<form>
<label>Progress: </label>
 <progress value="50" max="100">50%</progress>
</form>
 
</body>
</html>

Here we have a progress element, with 100 as max and 50 as it’s value. This way, the progress bar indicates that the progress is 50% complete. Also there is a text between the progress tag, which is used as a fall back text for browsers which do not yet support progress element of HTML5.

CSS file associated with this is same as present at pattern and title Attribute of Form Field: HTML5

progress element – progress bar: HTML5

[youtube https://www.youtube.com/watch?v=s1tfYfCpZx8]

YouTube Link: https://www.youtube.com/watch?v=s1tfYfCpZx8 [Watch the Video In Full Screen.]

Change the number present in value and max attribute and look at the visual effect/indication of the progress on the browser.

Note: In real time application development, you could fetch the numbers for value and max attribute dynamically using JavaScript. This way, the effects will be real and it creates the illusion that the progress is being made!

callback methods / anonymous functions: jQuery

Today lets see how callback methods or anonymous functions work. We also show you the anatomy of callback methods.

callback-method-anonymous-function-javascript-jquery-nodejs

callback methods are very important for achieving asynchronous way of coding.

HTML file
index.html

< !DOCTYPE html>
<html>
<head>
<title>callback or anonymous function</title>
<script src="jquery-1.10.2.min.js"></script>
<script src="myScript.js"></script>
</head>
<body>
 
<p></p>
<div></div>
 
</body>
</html>

Here we have included jQuery library and myScript.js We also have a paragraph tag and a div tag, to be filled with some data by myScript.js file.

JavaScript file
myScript.js

$(document).ready(function(){
 $("p").hide("slow");
 alert("Stop!");
});

Here the paragraph hide is called and before it finishes hiding, alert is called and every other operation of the webpage is halt until the user responds to the alert window. But if we want the paragraph to be hidden first and only after the paragraph is completely hidden we need to call the alert, in such case use callback methods as shown below:

JavaScript file: callback method
myScript.js

$(document).ready(function(){
 $("p").hide("slow", function(){
        alert("Stop!");
 });
});

If you want multiple things to occur after hiding the text(in above case) , you can nest the callback methods.

Anatomy of callback methods
JavaScript file: callback method
myScript.js

$(document).ready(function(){
eat("pizza", "cola", function(){
$("div").html("I had my food!");
});
 
});
 
function eat(food, drink, callback)
{
$("p").html("I ate "+food+" and had a "+drink);
 
if(callback && typeof(callback) === "function" )
{
callback();
}
 
}

Here we have a method called eat, which takes 3 parameters. First two are variable type and the 3rd parameter is a function type argument.

Once the page loads, we call eat method and pass pizza, cola and a callback method to it. After the first 2 variable values are displayed, eat method checks if the 3rd parameter is actually present and is a function – if so, it’ll call the function. So, the callback method is called after its preceding arguments are processed.

Anatomy and Working of Callback methods / anonymous functions

[youtube https://www.youtube.com/watch?v=lIPOER59ZSY]

YouTube Link: https://www.youtube.com/watch?v=lIPOER59ZSY [Watch the Video In Full Screen.]

Examples:
1. If we have calls to Facebook API, Twitter API and Google Finance API’s: Using JavaScript(jQuery or nodejs) we could send the request to all these API’s concurrently and not worry much about its response time. Once any of these API’s respond, the corresponding callback methods are called. So while these scripts are executed, it binds the callback methods to its calls, and then stops worrying about its response!

2. Many ad networks have implemented asynchronous ad codes, since these codes use callback methods and there is no need for the webpage to wait until the ad server responds. If and when the ad server responds with an ad, the page or the ad spot is filled with the ad.

color Input Type: HTML5

color input type fields expect the user to pick the color from the color palette. Once the user selects the color its corresponding hexadecimal value is being stored in the input field.

Demo

There are jQuery plugins to accomplish this task, but with HTML5 we need not use any plugins to accomplish this!

HTML file
index.html

< !DOCTYPE html>
<html>
<head>
<title>color Input Type: HTML5</title>
<link href="myStyle.css" rel="stylesheet" />
<script src="myScript.js"></script>
</head>
<body onload="fetch()">
 
<div>
<label for="color">Color pick: </label>
 <input name="color" type="color" id="get" onchange="fetch()"/><br />
<label for="hexa">Hex Code: </label>
 <input name="hexa" type="text" id="put"/><br />
</div>
 
</body>
</html>

Here we have 2 input fields of type color and text respectively. Once the user selects a color from the color palette, the corresponding hexadecimal value is shown in the text input type field.

JavaScript file
myScript.js

function fetch()
{
var get = document.getElementById("get").value;
document.getElementById("put").value = get;
}

Once the fetch method is called: it fetches the value present in the (color)input field and assigns it to text input field.

CSS file associated with this is same as present at pattern and title Attribute of Form Field: HTML5

Form Input Type – color: HTML5

[youtube https://www.youtube.com/watch?v=MiCOVDrVH44]

YouTube Link: https://www.youtube.com/watch?v=MiCOVDrVH44 [Watch the Video In Full Screen.]

Note: In real production server, you need not use two input fields as shown in this video tutorial. You can simply make use of the color input type and once you submit the form, you’ll get hexadecimal code value in place of the color input field. If you have a large audience still using Internet Explorer or other older browsers, then you can use jQuery plugin to accomplish the same task across all major browsers.

date time Input Type: HTML5

Today lets learn some very important input types of HTML5:

datetime
datetime-local
date
time
week
month

datetime input type is supported by Opera browser, but as of now(2013), Google Chrome doesn’t support it. All other input date time related input types are supported by Google Chrome.

HTML file: month input type
index.html

< !DOCTYPE html>
<html>
<head>
<title>date picker: HTML5</title>
<link href="myStyle.css" rel="stylesheet" />
</head>
<body>
 
<form>
<label for="dt">Date: </label>
 <input name="dt" type="month" min="2013-01" max="2013-09"/>
 <input type="submit"/>
</form>
 
</body>
</html>

Here we have a month type input field which has a minimum allowed month as 2013-01 and a maximum allowed month as 2013-09.

HTML file: date input type
index.html

< !DOCTYPE html>
<html>
<head>
<title>date picker: HTML5</title>
<link href="myStyle.css" rel="stylesheet" />
</head>
<body>
 
<form>
<label for="dt">Date: </label>
 <input name="dt" type="date"/>
 <input type="submit"/>
</form>
 
</body>
</html>

Here we have a date input type, which shows a date picker in the UI.

HTML file: time input type
index.html

< !DOCTYPE html>
<html>
<head>
<title>date picker: HTML5</title>
<link href="myStyle.css" rel="stylesheet" />
</head>
<body>
 
<form>
<label for="dt">Date: </label>
 <input name="dt" type="time"/>
 <input type="submit"/>
</form>
 
</body>
</html>

Here we have a time input type, we could even specify the fractional seconds. Look for the syntax at the end of this post.

HTML file: datetime input type
index.html

< !DOCTYPE html>
<html>
<head>
<title>date picker: HTML5</title>
<link href="myStyle.css" rel="stylesheet" />
</head>
<body>
 
<form>
<label for="dt">Date: </label>
 <input name="dt" type="datetime"/>
 <input type="submit"/>
</form>
 
</body>
</html>

datetime input type which signifies Universal Time Convention(UTC).

HTML file: datetime-local input type
index.html

< !DOCTYPE html>
<html>
<head>
<title>date picker: HTML5</title>
<link href="myStyle.css" rel="stylesheet" />
</head>
<body>
 
<form>
<label for="dt">Date: </label>
 <input name="dt" type="datetime-local"/>
 <input type="submit"/>
</form>
 
</body>
</html>

Here we have a datetime-local input type, which takes the input based on the local time zone of the user’s machine.

HTML file: week input type
index.html

< !DOCTYPE html>
<html>
<head>
<title>date picker: HTML5</title>
<link href="myStyle.css" rel="stylesheet" />
</head>
<body>
 
<form>
<label for="dt">Date: </label>
 <input name="dt" type="week"/>
 <input type="submit"/>
</form>
 
</body>
</html>

week input type gives date picker UI and allows user to select the entire date.

Form Input Type – date time: HTML5

[youtube https://www.youtube.com/watch?v=VKRuSryBaNk]

YouTube Link: https://www.youtube.com/watch?v=VKRuSryBaNk [Watch the Video In Full Screen.]

Note:
We can specify value, min, max and step attributes for all these input types. And the format for it is as shown below:

date YYYY-MM-DD default step 60 seconds

time HH:MM:SS.FF default step 1 Day (SS.FF means seconds and fractional seconds)

datetime YYYY-MM-DDTHH:MM:SS.FFZ default step 60 seconds (T and Z means the TimeZone, these alphabets/characters must be literally present in the format)

datetime-local YYYY-MM-DDTHH:MM:SS.FF default step 60 seconds (albhabet/character/letter T must be literally present in the format)

week YYYY-WNN default step of 1 week (letter W means the week, this alphabet/characters must be literally present in the format)

month YYYY-MM default step of 1 month