JAVASCRIPT.PROGRAMOWANIE OBIEKTOWE PDF

JS programowanie obiektowe. 1. JavaScript Programowanie Obiektowe Piotr Czajkowski [email protected]; 2. constructor new. Poznasz i zrozumiesz najnowsze mechanizmy JS (ES6+) Programowanie obiektowe z użyciem słów kluczowych class, extends itd. In the early nineties, a thing called object-oriented programming stirred up the software industry. Most of the ideas behind it were not really new at the time, but.

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We could of course just type [“n”, “ne”, Ah, tragedy of nature.

We used only three functions, makeReachedListstoreReachedand findReached to interact with javascript.programowani. Every object is based on a prototype, which gives it a set of inherent properties. And if, at some point, you find that you really need it, you can search the web, do some research, and figure out an approach that works for your situation.

JavaScript Programowanie obiektowe

It clones the object, and calls its construct method, if there is such a method, giving it the arguments that were passed to create. Some languages provide ways to explicitly declare certain methods and properties ‘private’, and make it an error to use them from outside the object. As far as I am concerned, obiekrowe prototype itself is the most important aspect of an object obuektowe, and the constructor is just an extension of that, a special kind of method.

Consider reading the third edition instead.

Justyna Walkowska (Translator of JavaScript. Programowanie obiektowe)

In fact there are, as usual, multiple good approaches to this. You only have to keep the interface in mind, and do not have to worry about the rest unless you are changing the object itself. It starts with an energy of 10and behaves in the following way:. Because you can use it to look things up by name, we will call it a Dictionary. For example, if SmallItem would, for some reason, also define an inspect method, which obieektowe method should obirktowe new prototype use?

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For example, we could give all objects a method called propertieswhich returns an array with the names of the non-hidden properties that the object has: One can use an array of arrays, like this:. A better approach would be to store the characters and the corresponding bug-constructors in a dictionary, and look for them there:.

This way, objects of the new type can be polymorphically used in all the places where objects of the old type could be used. What I want to do is warn the reader against developing an unhealthy attachment to them. Such a printer only takes one argument, so after partially applying it there are no arguments left, and it becomes a function of zero arguments.

I failed to find a really good way to prevent these creatures from either going extinct right away or gobbling up all lichen-eaters and then going extinct.

Prototypes are a powerful, if somewhat confusing, part of the way JavaScript objects work. Personally, I treat writing documentation as a ‘finishing touch’ to add to a system. This allows us to have all kinds of bugs, without changing anything about the terrarium code. Unless you are very lucky, the lichen-eaters will probably still go extinct after a while, because, in a time of mass starvation, they crawl aimlessly back and forth through empty space, instead of finding the lichen that is sitting just around the corner.

When outside code is accessing every single property and detail in the object, you can not change any of them without also updating a lot of other code. JavaScript does not, so you will have to rely on comments to describe the interface to an object.

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To look up the direction these names refer to, the following dictionary object is useful:. Getting a list of the property names in a dictionary sounds like a useful tool to have, so we add it to the Dictionary prototype. Instead of adding arguments to a function, this one adds a this object, using the first argument to the function’s apply method:.

Fortunately, all we have to do is to make the elementFromCharacter function more general. But I guess that can wait until we need it.

If there is no direction property, or an invalid one, it leaves the variables target and valueAtTarget undefined. Instead of providing regular functions for working with the objects, they provide a way to create such objects, using the new keyword, and a number of methods and properties that provide the rest of the interface.

In this chapter, we will discuss these ideas, along mavascript.programowanie JavaScript’s rather eccentric take on them.

In this case, we need to represent a grid of values, so I wrote a Grid type, which supports the operations that the terrarium will need. Three of the five supported actions need to know this, and the code obiejtowe be even uglier if they all computed it separately. We could put it into a function, but an even better approach is to write a constructor and a prototype specifically for situations like this, where we want to approach an object as just a set of properties.