Closure Library: Build Complex JavaScript Applications
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The document discusses the Google Closure Library for building complex, high-performance, and cross-browser JavaScript applications. It highlights challenges in JavaScript, such as lack of dependency and visibility controls, as well as the benefits of using the Closure Library and Compiler for object-oriented design, code optimization, and improved structure. The library provides reusable components, a namespace mechanism, and JSdoc annotations to enhance development efficiency and maintainability.
Closure Library: Build Complex JavaScript Applications
- 1. Closure Library: Build Complex JavaScript Applications Learn How Use Closure Library and Compiler to build web applications that are high-performance and cross-browser compatible
- 2. JavaScript Challenges Cross-Browser Compatibility No Dependency Mechanism No Namespace Mechanism No Visibility Controls No Type System No Static Checking Code Optimization and Minification Coding Style
- 3. Cross-Browser Compatibility Issues when working with the HTML DOM Different browsers’ JavaScript engines interpret and run the code differently Developers have to deal with browser quirks
- 4. No Dependency Mechanism Can't include or require other depent files from a javascript file Files used in a web page have to be specified in the html document using a script tag <script src="path/to/file.js"></script> If a javascript file needs other files to be loaded before it can run, the files have to be specified manually in the correct order
- 5. No Namespace Mechanism Most functions are part of the global namespace Variables may be defined in the global namespace by mistake function foo() { x= 10; } Garbage collection Only when variables/functions lose scope When including multiple files, variables or functions with same name are overwritten
- 6. No Visibility Controls, No Type System and No Static Checking JavaScript does not provide visibility controls for the properties and methods of a class, like public, protected or private. This allows other code to access properties or methods that are not supposed to be public. JavaScript does not provide a type system, meaning to that you can pass parameters of any type to a function If the function is designed to accept a numeric parameter, and you pass a string, this issue cannot be caught until runtime, when an error occurs. JavaScript does not provide static checking. This is related to the lack of a type system, and errors like wrong parameter type passed to function could be checked by the compiler.
- 7. Code Optimization and Minification JavaScript does not provide a way, built into the language itself, to optimize and minify the code. Closure Compiler
- 8. Closure Library Google Closure Library is the base JavaScript library for many Google products Search, Gmail, Maps, Calendar, Google+ and more. Open-source Library, not Framework A library is a set of components that you can use without any restrictions on how or where to write your code. Suitable for more complex applications, with a larger codebase, usually developed by a team
- 9. Closure Library Reusable Components Dependency and Namespaces Object-Oriented Server-Agnostic, Cross-Browser Compatibility JSDoc Annotations Closure Compiler
- 10. Reusable Components Large set of reusable components DOM manipulation User Interface Components Event Handling Server Communication Daata Structures and more
- 11. Dependency and Namespaces Closure library provides an interesting namespace mechanism, similar to the import statements in java or use statements in php. goog.provide("my.company.app"); goog.require("my.company.data.model");
- 12. Object-Oriented Closure library allows you to write object-oriented JavaScript and take advantage of the concepts of abstraction, encapsulation, inheritance and polymorphism. The code you will write is more maintainable, reusable and scalable.
- 13. Server-Agnostic, Cross-Browser Compatibility Closure library is server agnostic and cross browser compatible; it is also well tested and documented.
- 14. JSDoc Annotations By using the JS doc annotations you can document your code, specify the input type for the parameters of functions, the types of properties or the types of values returned by functions. These annotations will be used by the closure compiler to check and catch possible runtime errors at compile time.
- 15. Closure Compiler Closure compiler is used optimize and minify JavaScript code It removes dead code (code that is not being called) It checks the syntax, variable references, parameter types It also rewrites and minimizes into compact and high performance code
- 16. Closure Library: Build Complex JavaScript Applications Learn How Use Closure Library and Compiler to build web applications that are high-performance and cross-browser compatible