tailieunhanh - Lecture Web technology and online services: Lesson 4 - Javascript

Lecture "Web Technology and online services: Lesson 4 - Javascript" provide students with knowledge about: Client-side programming with JavaScript; JavaScript data types & expressions; Control statements; . Please refer to the detailed content of the lecture! | Javascript 1 Content Client-side programming with JavaScript scripts vs. programs JavaScript vs. JScript vs. VBScript common tasks for client-side scripts JavaScript data types amp expressions control statements functions amp libraries strings amp arrays Date document navigator user-defined classes 2 Client-Side Programming HTML is good for developing static pages can specify text image layout presentation links Web page looks the same each time it is accessed Client-side programming programs are written in a separate programming or scripting language . JavaScript JScript VBScript programs are embedded in the HTML of a Web page with HTML tags to identify the program component . the browser executes the program as it loads the page integrating the dynamic output of the program with the static content of HTML could also allow the user client to input information and process it might be used to validate input before it s submitted to a remote server 3 Scripts vs. Programs A scripting language is a simple interpreted programming language scripts are embedded as plain text interpreted by application simpler execution model don t need compiler or development environment saves bandwidth source code is downloaded not compiled executable platform-independence code interpreted by any script-enabled browser but slower than compiled code not as powerful full-featured JavaScript the first Web scripting language developed by Netscape in 1995 syntactic similarities to Java C but simpler more flexible in some respects limited in others loose typing dynamic variables simple objects JScript Microsoft version of JavaScript introduced in 1996 same core language but some browser-specific differences fortunately IE Netscape Firefox etc. can mostly handle both VBScript client-side scripting version of Microsoft Visual Basic 4 Common Scripting Tasks adding dynamic features to Web pages validation of form data probably the most commonly used application image rollovers .