javascript

Chapter 18: Advanced Techniques
Timers can be created in JavaScript using setTimeout() or setInterval()as follows:
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Timer code is placed into a holding area until the interval has been reached, at which point the
code is added to the JavaScript process queue to be executed the next time the JavaScript process
is idle.
Every time a piece of code executes completely, there is a brief amount of idle time to allow
other browser processes to complete.
This behavior means that timers can be used to split up long - running scripts into smaller chunks
that can be executed at a later time. Doing so helps the web application to be more responsive to
user interaction.
The observer pattern is used quite often in JavaScript in the form of events. Although events are used
frequently with the DOM, they can also be used in your own code by implementing custom events. Using
custom events helps to decouple different parts of code from one another, allowing easier maintenance
and reducing the chances of introducing an error by changing what seems to be isolated code.
Drag-and-drop is a popular user-interface paradigm for both desktop and web applications, allowing
users to easily rearrange or configure things in an intuitive way. This type of functionality can be created
in JavaScript using mouse events and some simple calculations. Combining drag-and-drop behavior
with custom events creates a reusable framework that can be applied in many different ways.
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