Java. Script l Java. Script — an object-oriented scripting programming language. Is a dialect of language ECMAScript. l Java. Script it is usually used as built in language for program access to objects of appendices. The widest application finds in browsers as language of scenarios for giving of interactivity to web pages. l The basic architectural lines: dynamic typification, weak typification, automatic control of memory, прототипное programming, functions as objects of the first class. l On Java. Script many languages have influenced, by working out was aim to make language similar on Java, but thus a lung for use by nonprogrammers. Language Java. Script any company or the organization that distinguishes him from a number of the programming languages used in web working out doesn't own. l The name «Java. Script» is the registered trade mark of company Oracle Corporation.
Creation preconditions l In 1992 company Nombas (subsequently got Openwave) has begun working out of built in scripting language Cmm, which, on a plan of developers, should become powerful enough to replace macroes, keeping thus similarity with Ci that to developers didn't make work to study it. Work with memory was the main difference from Ci. In a modern language all management of memory was carried out automatically: there was no necessity to create буферы, to declare variables, to carry out transformation of types. In the rest languages strongly resembled each other: in particular, Cmm supported standard functions and operators of Ci. Cmm has been renamed in Script. Ease as the initial name sounded too negatively, and the mention in it Ci "frightened off" people.
Creation preconditions l On the basis of this language has been created проприетарный product CEnvi. In the end of November, 1995 Nombas has developed version CEnvi introduced in web pages. Pages which could be changed by means of scripting language, have received name Espresso Pages — they showed use of scripting language for creation of game, check of the user input in forms and animation creations. Espresso Pages were positioned as a demoversion, called to help to present that happens, if in the browser language Cmm is introduced. They worked only in 16 -bit Netscape Navigator under control of Windows.
Founders l Before Brendanom Ajhom employed in company Netscape on April, 4 th, 1995, there was a task in view to introduce programming language Scheme or something similar in browser Netscape. As requirements have been washed away, Ajha have translated in the group responsible for server products where it has worked month, being engaged in improvement of report HTTP. In May the developer has been thrown back, in a command which is engaged in a client part (browser) where he has immediately started to develop the concept of a modern language of programming. Management of working out of the browser, including Tom Paquin, Michael Toja, Rick Schell, has been convinced that Netscape should support a programming language which is built in a HTML-code of page.
Founders l Besides Brendona Ajha in working out participated сооснователь Netscape Communications Mark Andrisin and сооснователь Sun Microsystems Bill Dzhoj: to have time to finish works on language to release of the browser, the companies have concluded the cooperation agreement in working out. They put before Marc Andreessen themselves aim to provide «language for pasting» making parts of a web resource: images, plug-ins, Java-applets which would be convenient for web designers and the programmers who are not possessing high qualification Bill Joy
l Originally language was called Live. Script and intended both for programming on the party of the client, and for programming on the server party (there it should be called Live. Wire). Syntax was influenced by languages of Si and Java, and as Java at that time was a fashionable word, on December, 4 th, 1995 Live. Script have renamed in Java. Script, having obtained the corresponding license at Sun. Announcement Java. Script from representatives Netscape and Sun has taken place on the eve of release of second beta version Netscape Navigator. In it it is declared that 28 in the lead IT Companies have expressed intention to use in the future products Java. Script as objective scripting language with the open standard. l In 1996 company Microsoft has let out the analog of language Java. Script named JScript. This language has been announced on July, 18 th, 1996. The first browser supporting this realization, was Internet Explorer 3. 0. l At the initiative of company Netscape standardization of language by association ECMA has been spent. The standardized version has name ECMAScript, is described by standard ECMA-262. To the first version of the specification corresponded Java. Script to version 1. 1, and also languages JScript and Script. Easy.
Language possibilities l Java. Script possesses a number of properties of object-oriented language, but the prototyping realized in language causes differences in work with objects in comparison with traditional objectoriented languages. Besides, Java. Script has a number of the properties inherent in functional languages — functions as objects of the first class, objects as lists, карринг, anonymous functions, short circuits — that gives to language additional flexibility.
Language possibilities l Despite syntax similar to Ci, Java. Script in comparison with language of Si has radical differences: 1. 2. 3. 4. 5. Objects, with possibility introspecial; Functions as objects of the first class ; Automatic reduction of types ; Automatic assemblage of garbage ; Anonymous functions. l In language there are no such useful things, as : Modular system: Java. Script doesn't give possibility to operate dependences and isolation of areas of visibility; 2. Standard library: in particular, there is no interface of programming of appendices on work with file system, to management of streams of input/conclusion, base types for the binary data ; 3. Standard interfaces to web servers and databases ; 4. The control system of packages which would trace dependences and automatically established them. 1.
Scope l Web applications Java. Script it is used in a client part of Web applications: client-server programs in which as the client the browser acts, and the server — the web server, having distributed between the server and the client to the logician. Information interchange in Web applications occurs on a network. One of advantages of such approach is that fact that clients don't depend on a concrete operating system of the user, therefore Web applications are crossplatformtion services 1. AJAX Java. Script it is used in AJAX, the popular approach to creation of interactive user interfaces of the Web applications, consisting in "a background" asynchronous data interchange of the browser with a Web server. As a result, at update of the data the web page doesn't reboot completely and the Web application interface becomes faster, than it happens at the traditional approach
Scope Comet — the umbellate term describing the mechanism of operation of Web applications, using constant HTTP connections that allows a Web server to send given to the browser without additional request from the browser. For such applications the technologies immediately supported by browsers are used. In particular, in them it is widely used Java. Script. l
Скачать презентацию Java Script l Java Script an object-oriented
Гагаринова Екатерина.ppt