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JavaScript

JavaScript. Teppo Räisänen LIIKE/OAMK 2011. HTML, CSS, JavaScript. HTML defines the structure CSS defines the layout JavaScript is used for scripting It adds functionality and interaction, and improves usability. General Information.

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JavaScript

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  1. JavaScript Teppo Räisänen LIIKE/OAMK 2011

  2. HTML, CSS, JavaScript • HTML defines the structure • CSS defines the layout • JavaScript is used for scripting • It adds functionality and interaction, and improves usability

  3. General Information • JavaScript (JS) is a programming language for interactie Web pages • Mouse event based functionalities • Input validation • Dynamic menus • JS is especially good for validating form input

  4. General Information • HTML does not provide means for input validation • Validation on server side (PHP…) is possible but slower (Why?) • There are plenty of available scripts for different kinds of validation processes

  5. JavaScript - Basics • JS scripts are usually executed on the client-side • The scripts are usually rather simple and small-scaled programs • The execution of the scripts is based on runtime interpreting

  6. JavaScript - Basics • JS is a fully-scaled programming language: • functions • control structures • string processing • The inbuilt functionalities of the JS have been specialized for control of a browser

  7. JavaScript & HTML • JS script can be embedded into a HTML page by • including scripting section into the head element • writing the script part into an .js file and including the file into the page • including the script into the definition of an HTML element

  8. Example 1 • Automatic focus to a form field • Without the script the user must point the mouse to the form field • The script is executed when the body of the page is loaded • The script will improve the usability of the page

  9. Example 2 • Validation of an email field • Validation on the client side is faster than server side validation • onsubmit-value is defined in the beginning tag of the form -> Validation happens when the form is being submitted • The function will recieve the HTML form as a parameter

  10. Compatibility • There are some issues with compatibility • Check • http://www.quirksmode.org/dom/events/

  11. HTML DOM • DOM • Document Object Model • http://www.w3schools.com/htmldom/default.asp • JavaScript can access HTML elements trough DOM • In JavaScript: • var object = document.getElementById(”elementId”); • object.value = ”interesting”;

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