Javascript fundamentals and not
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JavaScript is an object-based scripting language. It uses variables declared with var, and objects are collections of name-value pairs. JavaScript is case sensitive and always uses semicolons. Strict mode restricts actions and prevents errors. Key concepts include null, undefined, equality operators, namespaces, classes, functions, closures, and patterns like MVVM and Knockout.js for dynamic UIs.
![ http://en.wikipedia.org/wiki/Model_View_ViewModel
The Model View ViewModel (MVVM) is an architectural
pattern used in software engineering that originated
from Microsoft as a specialization of the presentation model
design pattern introduced by Martin Fowler.[1] Largely based on
the model–view–controller pattern (MVC), MVVM is targeted at
modern UI development platforms which support Event-driven
MVVM Pattern programming, such as HTML5,[2][3] Windows Presentation
Foundation(WPF), Silverlight and the ZK framework.
MVVM facilitates a clear separation of the development of
the graphical user interface (either as markup language or GUI
code) from the development of the business logic or back
end logic known as the model (also known as the data model to
distinguish it from the view model).](https://image.slidesharecdn.com/javascriptfundamentalsandnot-130205093936-phpapp01/85/Javascript-fundamentals-and-not-11-320.jpg)
Javascript fundamentals and not
- 1. JavaScript OBJECT -> “Namespace”, “classes”, “constructor”, prototypes, fluent “interface”, jQuery live example, MVVM, Knockoutjs
- 2. • JavaScript is object based, everything in JS is an object • Variables created using var • You should always use semicolons, and an object is a collection of name/value name: value • JavaScript is case sensitive • Always use strict mode, declared with “use strict” Restrictions Cannot use a variable without declaring it starter Cannot write to a read-only property Cannot add properties to non-extensible objects Cannot illegally delete functions and variables Cannot define a property more than once in an object literal Cannot use a parameter name more than once in a function Cannot use reserved words, eval, or arguments, as names for functions and variables The value of this in a function is no longer the window object Cannot declare functions inside of statements Cannot change the members of the arguments array
- 3. • NULL • One of the JavaScript primitive types • Represents the absence of value Null • Evaluates to false in Boolean expressions and • UNDEFINED • Primitive type undefined • Represents an unknown value • Returned when a non-existent object property is called • Evaluates to false in Boolean expressions
- 4. Objects are only equal to themselves Primitives are equal if the values match (“salvo” === “salvo”) Two sets of equality operators ( == and ===) Avoid coercive never use == or != INSTEAD of === or !== equality operators 0 == '0'; 0 === '0'; //true //false false == '0'; //true false === '0'; //false
- 5. Top-level function Simple way to test for numbers and failed mathematical isNaN expressions parseFloat method is helpful to convert a string in a number
- 6. Comparision == OR === DEMO Prototype
- 7. The window object in browsers is a global namespace Variables defined outside a function are in the global namespace Variables defined without the var keyword are in the global namespace Always create your own namespace by a pattern The module pattern was made by Eric Miraglia of YUI in the 2007 Use it to prevent name collisions and polluting parent namespace Keep everything tidy Module Export Pattern: Namespace var MODULE = (function () { var my = {}, privateVariable = 1; function privateMethod() { // ... } my.moduleProperty = 1; my.moduleMethod = function () { // ... }; return my; }()); Anonymous Closures Pattern: (function () { // ... all vars and functions are in this scope only // still maintains access to all globals }());
- 8. We create a class in js by a pattern Classes Use it to prevent name collisions and polluting parent namespace Keep everything tidy Use the new keyword to invoke the constructor
- 9. A function start with the keyword function A function can have a name or not A function can have parameters The delimiters of the function are { } A function can return a value, and that value can be itself Cannot be overloaded!!! Parameters not passed are setted undefined Functions Function without parameters has a default param called (arguments) Is possible to have a function inside a function Closure Functions have this Every function has a property named prototype Useful to add a new function to a “class”
- 10. Closure Class DEMO Namespace – Module Namespace – Inherit
- 11. http://en.wikipedia.org/wiki/Model_View_ViewModel The Model View ViewModel (MVVM) is an architectural pattern used in software engineering that originated from Microsoft as a specialization of the presentation model design pattern introduced by Martin Fowler.[1] Largely based on the model–view–controller pattern (MVC), MVVM is targeted at modern UI development platforms which support Event-driven MVVM Pattern programming, such as HTML5,[2][3] Windows Presentation Foundation(WPF), Silverlight and the ZK framework. MVVM facilitates a clear separation of the development of the graphical user interface (either as markup language or GUI code) from the development of the business logic or back end logic known as the model (also known as the data model to distinguish it from the view model).
- 12. Simplify dynamic JavaScript UIs by applying the Model-View- Knockoutjs ViewModel (MVVM)
- 13. Knockout – visible or invisible Knockout – list DEMO Matt and Leigh example
- 14. • Some useful links Strict Mode - http://msdn.microsoft.com/en-us/library/ie/br230269(v=vs.94).aspx • Strict Mode - http://ejohn.org/blog/ecmascript-5-strict-mode-json-and-more/ • Knockoutjs - http://knockoutjs.com/ • JavaScript info - https://developer.mozilla.org/en-US/docs/JavaScript/Reference/ • Namespace function - https://github.com/smith/namespacedotjs/blob/master/example/sandbox.js
Editor's Notes
- #8: Strict mode: http://www.nczonline.net/blog/2012/03/13/its-time-to-start-using-javascript-strict-mode/
- #12: Strict mode: http://www.nczonline.net/blog/2012/03/13/its-time-to-start-using-javascript-strict-mode/
- #13: Strict mode: http://www.nczonline.net/blog/2012/03/13/its-time-to-start-using-javascript-strict-mode/