The Idea of dynamic content on the web resoure become the norm. Static page and template building finally completed his mission.
However, modern web resource should not necessarily be represented by a set of pages generated by the server and updated by browser (JS+AJAX).
Web-resource in the time of arrival of the visitor can be a a couple of headlines for the record, some text in the “head”, a few lines of code in the “body” and all. The rest is “Thought” in the process the visitor is a great website, or those aspiring to be.
The Concept of the algorithm outside the function here is not in principle. Of course, the developer can anywhere on the page to insert the script, you can put in a code and it will be executed. But what is the point in the code that is executed only once at loading (overloading) Page? Is it possible to set the initial values of some irrelevant variables.
The Script is to place the description of variables and functions, than a good chunk of code written for himself. It is the set of functions is significant and meaningful, perhaps their mutual direct communication, but often all differently. Place the description of the function and place of its application is not the same.
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It is not necessary that the function will call another function directly, but it can be done indirectly through dynamic code generation. The visitor makes a decision under this code and works completely different system functions.
Functional dynamics is not only and not so much the handlers that are assigned to page elements, it functions forming the elements of the page, well, direct the handlers, too, can change.
The Action unfolds on the page depending on its elements and behavior of the visitor on it. Movement of the mouse, keyboard buttons, clicks, events, elements and other circumstances lead to start the desired functions.
This new thinking in development: distributed processing of the information in the depths of the individual browser!
Description the functions in the General case starts with the keyword “function” followed by its name, argument list in parentheses separated by a comma and the function body in curly brackets.
This example describes two functions that provide an AJAX exchange between page and server. Variable scXHR described above are thus available in InitXML and inside WaitReplySC.
It is also important to note that WaitReplySC is a function. But in the string ScXHR.onreadystatechange = WaitReplySC it is passed as a parameter. This is a General rule transfer of functions to other functions as parameters. Pointed brackets and gave them her option (parameters) - the function will be executed immediately. Gave only the name, but so what. The function call would someone got her name.
In the body of the function, you can write any language statements, which, in fact, is used for this purpose. Inside the function the variables available, described the inside and outside of it, but not those described inother functions.
Developers Usually honor this opportunity and, depending on the situation, decide to exit a function as soon as possible.
Not necessarily to run the whole algorithm functions when you can leave early.
Within the function, the arguments variable is available, has a property Length. You can refer to any argument of the function through arguments , arguments , ... to the latest arguments [arguments.length-1].
After the function exits, everything that was associated with its execution, will be destroyed. During the execution of the function can change the external variables, except those described in other functions, including domestic.
Basic care functions - to serve browser events. To do this, almost every tag has the ability to specify the event name and the function of its processing. You can specify multiple events, but each event is listed only one function.
One function can serve multiple page items and several events. By means of the parameter “this” you can pass functions information, where it was called.
A Classic use of JS functions, event handlers on the elements. In this example, in the form of entrance/exit of a visitor function will be invoked scfWecomeGo() or scfWelcomeCancel(), and the choice of mode scfMenuItemClick(this).
The Function must return a character string, a number or another function. It can return a full HTML element, and in which the required number of elements, with their handlers to its events.
Locating an element on the page, a developer creates new functionality, which is good in terms of solving the problem and meet the interests of visitors, but is quite difficult in the implementation.
Since such a full-featured development, easy to get lost in your own code, in function calls, in the moments when formed or that the content of a section of the page. Before making such direction development, will not prevent really think about it.
Allows the Developer to think at the level of all elements of the page-level events and to have a clear view of how things really are. It's hard, but worth it.
In this example, where previously the function was called, which initiated the creation of the menu item navigation files. It is assumed paging, that is, in the window a total of seven files that can be removed and processed. You can navigate to as a click on the line in the file, and arrow keys, and blocks for the seven lines.
In each case have their own function. In other words, in this simple example, you need to write a couple of dozen functions that will react to various events, and some of these functions will handle the various options and situations that the events are not relevant.
This is a good mechanism, but rather complex to implement. Technically all valid, semantically to provide the logic of the transmission “functional” only a qualified developer.
If the argument is a function, then pass a variable with special properties, that is, it is not a number, not a string, not an object. But the use of this argument may lead to changes of the external variables and the result of execution of the function. Depending on what is passed will be adequate.
If it is possible to do without the frills better to use it. All these options are good. Of course, in many cases is the only solution.
A Classic example of recursion: the factorial. There is quite difficult to write an algorithm that will loop, but it is very easy to go beyond the boundaries of the values. The factorial grows too fast.
However, the recursion, and a function that calls another function, which can make the callback a normal things.
For Example, a regular table. The table may be other tables. Nesting should not be restricted. To write for each table a different set of features - too much luxury.
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Alin Trodden - author of the article, editor
"Hi, I'm Alin Trodden. I write texts, read books, and look for impressions. And I'm not bad at telling you about it. I am always happy to participate in interesting projects."
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