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Unit 2 computer systems

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Main features of JavaScript - P3 Browser Support Control Data Validation Detecting a Users OS or Browser Browser Support To access certain content you need to have the necessary plug-in, for example to access flash content, you need to install the flash plug-in in your browser. But to use JavaScript, you don't have to use any plug-in at all. This is because all browsers have accepted JavaScript as a scripting language and so they provide integrated support for it. Control A great feature of JavaScript is the control you have over the browser. There are various things you can control such as the background colour, this feature servers more than one purpose. Most people would change the colour of a webpage just because the option is there but it can also be a huge help for people who are visually impaired. Data Validation Being able to validate a users input is another great feature of JavaScript. Most websites will have a section where you may need to input some data (contact form, registration and more) and if you were to enter your name in a section that is expecting numeric input you will get an error message. ...read more.


Image on the right shows what happens when you enter an invalid email address, the image on the left shows what happens when you enter a valid email address. Timer Design: - Separate document. Create: Header <script type="text/javascript"> function timedText() { var t1=setTimeout("document.getElementById('txt').value='1 Min!'",60000); var t2=setTimeout("document.getElementById('txt').value='2 Mins!'",120000); var t3=setTimeout("document.getElementById('txt').value='3 Mins!'",240000); } </script> Form <form> <input type="button" value="Display timed text!" onclick="timedText()" /> <input type="text" id="txt" /> </form> Test: This screenshot shows the timer in action, after every minuet (up to three minuets) the timer shows a message telling you how long you have been on that page. Implementation of Web Page Scripts in Two Different Browsers - M3 Not all browsers are able to implement scripts the same and the sear amount of browsers (and versions) makes it really hard to create a web page around a specific browser. As soon as you load a page that contains JavaScript you can see the differences in implementation between IE and FF straight away, Internet Explorer requires confirmation from you before it runs the script, Firefox on the other hand loads it right away. Yes there are a few security issues with Firefox automatically running scripts but you should never run into serious trouble. ...read more.


Buttons - Everyone loves buttons, forward, back or even change the colour. Alerts - Messages that pops up to tell your visitors important information. Prompts - Like an Alert except they want input from you. Data Validation - Make sure your viewers input is correct by validating what's been entered. Clocks - It's always nice to know how much time you have wasted. Browser and OS detection - Simply shows you your OS and Browser info. Redirecting - This page no longer in use? No problem, redirect them to the new one. These are just a few example of how you would improve/create interactivity in your webpage. Below is an example of how you would change the background colour of your site, this not only adds the interactivity of the site but also helps people who have visual impairments, I chose red, green and white <form> <INPUT type="button" value="Change to Yellow!" name="button3" onClick="document.bgColor='green'"> <br> <INPUT type="button" value="Change to Red!" name="button4" onClick="document.bgColor='red'"> <br> <INPUT type="button" value="Change back!" name="button5" onClick="document.bgColor='white'"> </form> Evaluate the impact of using CSS to control layout - D3 changing the layout of a webpage using HTML and tables can be a pain, not every browser loads them the same and breaking can occur. Fortunately when CSS was introduced ?? ?? ?? ?? ...read more.

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