HTML5 Interview Questions And Answers

HTML5 is being developed as the next major revision of HTML (HyperText Markup Language), the core markup language of the World Wide Web. The Web Hypertext Application Technology Working Group (WHATWG) started work on the specification in June 2004 under the name Web Applications 1.0. As of March 2010, the specification is in the Draft Standard state at the WHATWG, and in Working Draft state at the W3C.

► The canvas element: Canvas consists of a drawable region defined in HTML code with height and width attributes. JavaScript code may access the area through a full set of drawing functions similar to other common 2D APIs, thus allowing for dynamically generated graphics. Some anticipated uses of the canvas include building graphs, animations, games, and image composition.
► Timed media playback
► Offline storage database
► Document editing
► Drag-and-drop
► Cross-document messaging
► Browser history management
► MIME type and protocol handler registration

HTML5 is the proposed next standard for HTML 4.01, XHTML 1.0 and DOM Level 2 HTML. It aims to reduce the need for proprietary plug-in-based rich internet application (RIA) technologies such as Adobe Flash, Microsoft Silverlight, Apache Pivot, and Sun JavaFX.

► Cleaner markup
► Standardized approach to mobile devices support
► Additional semantics of new elements like <header>, <nav>, and <time>
► New form input types and attributes that will (and in Opera’s case, do) take the hassle out of scripting forms.

The new HTML5 specification allows browsers to prefetch some or all of a website assets such as HTML files, images, CSS, JavaScript, and so on, while the client is connected. It is not necessary for the user to have accessed this content previously, for fetching this content. In other words, application cache can prefetch pages that have not been visited at all and are thereby unavailable in the regular browser cache. Prefetching files can speed up the site’s performance, though you are of course using bandwidth to download those files initially.

HTML5 is the latest version of HTML standard supporting multimedia and graphical content.

HTML5 introduced many elements such as , instead of to support multimedia.

a) Cleaner markup
b) Additional semantics of new elements like <header>, <nav>, and <time>
c) New form input types and attributes that will (and in Opera’s case, do) take the hassle out of scripting forms.

We can display video using the tag as shown below:

<video width=“320″ height=“240″ controls=“controls”>
<source src=“test.mp4″ type=“video/mp4″ />
</video>

HTML5 offers two new objects for storing data on the client:

LocalStorage – stores data with no time limit

<script type=“text/javascript”>
localStorage.lastname=“ZAG”;
document.write(localStorage.lastname);
</script>

SessionStorage – stores data for one session.The data is deleted when the user closes the browser window.

<script type=“text/javascript”>
sessionStorage.lastname=“ZAG”;
document.write(sessionStorage.lastname);
</script>

We can display audio using the tag as shown below:

<audio controls=“controls”>
<source src=“test.mp3″ type=“audio/mp3″ />
</audio>

HTML5 specification allows browsers to prefetch some or all of a website assets such as HTML files, images, CSS, JavaScript, and so on, while the client is connected. It is not necessary for the user to have accessed this content previously, for fetching this content. In other words, application cache can prefetch pages that have not been visited at all and are thereby unavailable in the regular browser cache. Prefetching files can speed up the site’s performance, though you are of course using bandwidth to download those files initially.

HTML5 is the proposed next standard for HTML 4.01, XHTML 1.0 and DOM Level 2 HTML. It aims to reduce the need for proprietary plug-in-based rich internet application (RIA) technologies such as Adobe Flash, Microsoft Silverlight, Apache Pivot, and Sun JavaFX.

The canvas element is used to draw graphics images on a web page by using javascript like below

<canvas id=“pcdsCanvas” width=“500″ height=“400″>
</canvas>
<script type=“text/javascript”>
var pcdsCanvas=document.getElementById(“phpzagCanvas”);
var pcdsText=pcdsCanvas.getContext(“2d”);
pcdsText.fillStyle=“#82345c”;
pcdsText.fillRect(0,0,150,75);
</script>

The sessionStorage object stores the data for one session. The data is deleted when the user closes the browser window. like below we can create and access a sessionStorage here we created “name” as session

<script type=“text/javascript”>
sessionStorage.name=“PHPZAG”;
document.write(sessionStorage.name);
</script>

Before HTML5 LocalStores was done with cookies. Cookies are not very good for large amounts of data, because they are passed on by every request to the server, so it was very slow and in-effective.

In HTML5, the data is NOT passed on by every server request, but used ONLY when asked for. It is possible to store large amounts of data without affecting the website’s performance.and The data is stored in different areas for different websites, and a website can only access data stored by itself.

And for creating localstores just need to call localStorage object like below we are storing name and address

<script type=“text/javascript”>
localStorage.name=“PHPZAG”;
document.write(localStorage.name);
</script>
<script type=“text/javascript”>
localStorage.address=“Newyork USA”;
document.write(localStorage.address);
</script>

The canvas element is used to draw graphics images on a web page by using javascript like below

Like below we can add video in html5

<video width=“320″ height=“240″ controls=“controls”>
<source src=“mysong.mp4″ type=“video/mp4″ />
<source src=“mysong.ogg” type=“video/ogg” />
</video>

And audio like this

<audio controls=“controls”>
<source src=“mysong.ogg” type=“audio/ogg” />
<source src=“mysong.mp3″ type=“audio/mpeg” />
</audio>

Yes we can use below new input type Attribute in HTML5
Type: Value:
tel The input is of type telephone number
search The input field is a search field
url a URL
email One or more email addresses
datetime A date and/or time
date A date
month A month
week A week
time The input value is of type time
datetime-local A local date/time
number A number
range A number in a given range
color A hexadecimal color, like #82345c
placeholder Specifies a short hint that describes the expected value of an input field

Below are the New Media Elements have added in HTML5
Tag Description
<audio> For multimedia content, sounds, music or other audio streams
<video> For video content, such as a movie clip or other video streams
<source> For media resources for media elements, defined inside video or audio
elements
<embed> For embedded content, such as a plug-in
<track> For text tracks used in mediaplayers

yes we can use Canvas element in html5 like <canvas></canvas>

Below are the New Markup Elements added in HTML5
Tag Description
<article> Specifies independent, self-contained content, could be a news-article, blog post, forum post,
or other articles which can be distributed independently from the rest of the site.
<aside> For content aside from the content it is placed in. The aside content should
be related to the surrounding content
<bdi> For text that should not be bound to the text-direction of its parent elements
<command> A button, or a radiobutton, or a checkbox
<details> For describing details about a document, or parts of a document
<summary> A caption, or summary, inside the details element
<figure> For grouping a section of
stand-alone content, could be a video
<figcaption> The caption of the figure section
<footer> For a footer of a document or section, could include the name of the author, the
date of the document, contact information, or copyright information
<header> For an introduction of a document or section, could include navigation
<hgroup> For a section of headings, using <h1> to <h6>, where the largest is the main
heading of the section, and the others are sub-headings
<mark> For text that should be highlighted
<meter> For a measurement, used only if the maximum and minimum values are known
<nav> For a section of navigation
<progress> The state of a work in progress
<ruby> For ruby annotation (Chinese notes or characters)
<rt> For explanation of the ruby annotation
<rp> What to show browsers that do not support the ruby element
<section> For a section in a document. Such as chapters, headers, footers, or any
other sections of the document
<time> For defining a time or a date, or both
<wbr> Word break. For defining a line-break opportunity.

The <!DOCTYPE> is an instruction to the web browser about what version of HTML the page is written in. AND The <!DOCTYPE> tag does not have an end tag and It is not case sensitive.

The <!DOCTYPE> declaration must be the very first thing in HTML5 document, before the <html> tag. As In HTML 4.01, all <! DOCTYPE > declarations require a reference to a Document Type Definition (DTD), because HTML 4.01 was based on Standard Generalized Markup Language (SGML). WHERE AS HTML5 is not based on SGML, and therefore does not require a reference to a Document Type Definition (DTD).

HTML5 is nothing more then upgraded version of HTML where in HTML5 Lot of new future like Video, Audio/mp3, date select function , placeholder , Canvas, 2D/3D Graphics, Local SQL Database added so that no need to do external plugin like Flash player or other library

I think yes but as compare to our current internet connections is not too much heavy.