Event Listeners in programming

[VAIJAYI]

Hello my friends , I am really very impressed about this forum and the question being covered in this forums as it is not just restricted to a certain area and expertise , so I too have an question that has something to do with the programming stuffs and I will appreciate if you could tell me about the event driven programming and I have heard there are interfaces are there if you talked about the events , if you have any sort of knowledge on this then please do not hesitate to share with me.

[Steyn]

If you want to learn about the programming then I think you should learn the basic things first such as the data types and the manipulations being done with the help of basic calculation , then jump to the event driven programming . This event driven programming depend on the event such as click event or double click or button press event, you will have to write codes on their related procedures and then work accordingly. If talked about Java to have an event driven task it makes use of event listeners.

[Vandam]

Adding a typical DOM event listener to a web page is reasonably simple Javascript. The first thing we require to think is that not all browsers support this up till now so we will want to include a test to see if this "characteristic" is supported. Here is an example that shows a brief example that will give you the idea about the event listener .

var a = document.getElementById('myarea');
if (a.addEventListener)
a.addEventListener('keyup',eventkeyup,false );

[Jacques25]

I will comment on the example given above . This code appends an event listener to the object in the web page recognized by the id 'myarea' (given that the web browser supports event listeners). The action that the event listener is triggered by in this example is a keyup event. Make a note that when we utilize event listeners we do not append the word on to the front the way that we did with conventional event handlers.

[Steyn]

When this event listener accepts a keyup event in the mentioned example it invokes the eventkeyup() method . Note that we do not comprise the parentheses in the program here because we do not wish the method to execute straight away. This does not much differ from the method that we left off the parentheses while using the conventional Javascript method of event handling such as the init method .