Inside a constructor, the keyword this references the new object that's being created. Instead, by referring to an options object defined within the plugin namespace explicitly (for example, $fn.pluginName.options) and merging this with any options passed through to the plugin when it is initially invoked, users have the option of either passing options through during plugin initialization or overriding options outside of the plugin (as demonstrated here). From a structure perspective, a CommonJS module is a reusable piece of JavaScript which exports specific objects made available to any dependent code. Note: This particular variation of the Decorator pattern is provided for reference purposes. This allows us to synchronize Models and ViewModels when the value of a Model attribute is modified. This book covers Javascript design patterns, MV* patterns, Modern Modular patterns to design pattern … Let's go through some more code: Extensibility is of course key to any scalable namespacing pattern and IIFEs can be used to achieve this quite easily. They are truly beneficial if we wish to create easily-readable structures that can be expanded to support deep nesting. Instead of binding to the events of the individual nodes, a higher level object is given the responsibility of notifying subscribers about interaction events. State is a topic which is regularly discussed when looking at Single-page applications, where the concept of state needs to be simulated. The important meta-data for each book could probably be broken down as follows: We'll also require the following properties to keep track of which member has checked out a particular book, the date they've checked it out on as well as the expected date of return. Views and controllers have a slightly different relationship. In the following example, a library function is defined which declares a new library and automatically binds up the init function to document.ready when new libraries (i.e. The general idea behind the Command pattern is that it provides us a means to separate the responsibilities of issuing commands from anything executing commands, delegating this responsibility to different objects instead. We saw earlier that Object.create allows us to initialise object properties using the second supplied argument. As we saw in our initial ViewModel example, the ViewModel doesn’t just expose Model attributes but also access to other methods and features such as validation. A design pattern should have a: Design patterns are quite a powerful approach to getting all of the developers in an organization or team on the same page when creating or maintaining solutions. A mediator, though, might use events to make decisions, but it is definitely not “fire and forget”. This can mean an increased amount of work to perform lookups, however developers such as Juriy Zaytsev have previously tested and found the performance differences between single object namespacing vs the "nested" approach to be quite negligible. For example, a menu system might have a view that handles the menu item clicks. Imagine we have the following handler prior to adding any timers: If we wished to add a hard delay before the active class was added, we could use setTimeout() to achieve this. It could run its logic and process to facilitate and coordinate many objects that are related to each other, but unrelated to the original event source. It's not always clear if a piece of code we're looking at is following a set pattern or just accidentally happens to appear like it does. This effectively allows us to import them and locally alias them as we wish. Whilst it may look like quite a lot of work in the explanation above, now that we have a generic getBindings method written, it’s a lot more trivial to simply re-use it and use data-classes rather than strict data-bindings for writing our KnockoutJS applications instead. Below is an example of an implementation of interfaces in JavaScript using duck-typing - an approach that helps determine whether an object is an instance of constructor/object based on the methods it implements.
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