3 ways to define a JavaScript class
Introduction JavaScript is a very flexible object-oriented language when it comes to syntax. In this article you can find three ways of defining and instantiating an object. It's important to note that there are no classes in JavaScript. 1. This is probably one of the most common ways. function Apple (type) { this.type = type; this.color = "red"; this.getInfo = getAppleInfo; } function getAppleInfo() { return this.color + ' ' + this.type + ' apple'; } To instantiate an object using the Apple constructor function, set some properties and call methods you can do the following: var apple = new Apple('macintosh'); apple.color = "reddish"; alert(apple.getInfo()); 1.1. In the example above you see that the method getInfo() of the Apple "class" was defined in a separate function getAppleInfo(). function Apple (type) { this.type = type; this.color = "red"; this.getInfo = function() { return this.color + ' ' + this.type + ' apple'; }; } 1.2. 2. apple.color = "reddish"; alert(apple.getInfo()); 3.
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Inversion of Control Containers and the Dependency Injection pattern
In the Java community there's been a rush of lightweight containers that help to assemble components from different projects into a cohesive application. Underlying these containers is a common pattern to how they perform the wiring, a concept they refer under the very generic name of "Inversion of Control". In this article I dig into how this pattern works, under the more specific name of "Dependency Injection", and contrast it with the Service Locator alternative. The choice between them is less important than the principle of separating configuration from use. One of the entertaining things about the enterprise Java world is the huge amount of activity in building alternatives to the mainstream J2EE technologies, much of it happening in open source. Underlying these containers are a number of interesting design principles, things that go beyond both these specific containers and indeed the Java platform. Components and Services A Naive Example class MovieLister... Inversion of Control
Object-Oriented Programming with JavaScript, Part I: Inheritance: Inheritance through Functions - Doc JavaScript - Webreference.com
Object-Oriented Programming with JavaScript, Part I: Inheritance Inheritance through Functions Although JavaScript does not support an explicit inheritance operator, you can implement inheritance in other ways. There are two different ways to establish a hierarchy of classes in JavaScript. The first method to create an object as a subclass of another object, is to call the superclass constructor function inside the subclass object definition. function superClass() { this.bye = superBye; this.hello = superHello; } function subClass() { this.inheritFrom = superClass; this.inheritFrom(); this.bye = subBye; } function superHello() { return "Hello from superClass"; } function superBye() { return "Bye from superClass"; } function subBye() { return "Bye from subClass"; } function printSub() { var newClass = new subClass(); alert(newClass.bye()); alert(newClass.hello()); } Convince yourself that it is working correctly. this.inheritFrom = superClass; this.inheritFrom(); Let's take another example.
Learning Javascript with Object Graphs
HEADS UP! This article was written for an older version of node. More up-to-date information may be available elsewhere. One of the secrets to being a super effective JavaScript developer is to truly understand the semantics of the language. This article will explain the basic elemental parts of JavaScript using easy to follow diagrams. References Everywhere A variable in JavaScript is simply a label that references a value in memory somewhere. Local Variables In the following example, we will create four local variables in the top-level scope and point them to some primitive values: variables.js // Let's create some local variables in the top scopevar name = "Tim Caswell";var age = 28;var isProgrammer = true;var likesJavaScript = true;// Test to see if the two variables reference the same valueisProgrammer === likesJavaScript; Notice that the two boolean variables point to the same value in memory. The outer box represents the outermost closure scope. Objects and Prototype Chains objects.js
Inversion of Control Containers and the Dependency Injection pattern
In the Java community there's been a rush of lightweight containers that help to assemble components from different projects into a cohesive application. Underlying these containers is a common pattern to how they perform the wiring, a concept they refer under the very generic name of "Inversion of Control". In this article I dig into how this pattern works, under the more specific name of "Dependency Injection", and contrast it with the Service Locator alternative. The choice between them is less important than the principle of separating configuration from use. One of the entertaining things about the enterprise Java world is the huge amount of activity in building alternatives to the mainstream J2EE technologies, much of it happening in open source. A lot of this is a reaction to the heavyweight complexity in the mainstream J2EE world, but much of it is also exploring alternatives and coming up with creative ideas. Components and Services A Naive Example class MovieLister...
Inheritance and the prototype chain - JavaScript
JavaScript is a bit confusing for developers experienced in class-based languages (like Java or C++), as it is dynamic and does not provide a class implementation (although the keyword class is a reserved keyword and cannot be used as a variable name). When it comes to inheritance, JavaScript only has one construct: objects. Each object has an internal link to another object called its prototype. That prototype object has a prototype of its own, and so on until an object is reached with null as its prototype. null, by definition, has no prototype, and acts as the final link in this prototype chain. While this is often considered to be one of JavaScript's weaknesses, the prototypal inheritance model is in fact more powerful than the classic model. Inheritance with the prototype chain Inheriting properties JavaScript objects are dynamic "bags" of properties (referred to as own properties) and each one has a link to a prototype object. In this example, someObject. Inheriting "methods"
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