AJAX interview questions Part-2

1. Ques:What are the differences between AJAX and JavaScript ?

Answer:

• AJAX sends request to the server and will not wait for the response.
• It will allow other operations on the page before it get response of previous request; whereas, JavaScript make a request to the server, will waits for response and will not allow other operation on the page during that time.
• In AJAX, the page will not get refreshed for downloading the whole page while JavaScript manages and controls a Web page after being downloaded.
• By using AJAX we can minimize the overload on the server because the script needs to request once while JavaScript posts the request that updates the script each time.

2. Ques: How many types of triggers are there in update panel?
Answer:
Triggers are the stored procedures used in the database. There are 2 types of triggers in update panel, which are as follows:

1. PostBackTrigger : This trigger is the internal trigger of the update control. It doesn’t work asynchronously. It short circuits the control to do synchronous post back. For example Update control panel

2. AsyncPostBackTrigger : This trigger is a control, that is external to update control. It works synchronously. It wires up the control to do asynchronous post back.


3. Ques: What is an Timer control in ajax?
Answer:
By using Timer control we can update the particular content of the page automatically without clicking the browser refresh button. The Timer control is used along with the Update Panel so the Contents put under the update panel are automatically updated according the timing set under the timer_click event.


4. Ques: How can we cancel the XMLHttpRequest in AJAX?
Answer:
Abort() method can be called to cancel the XMLHttpRequest in Ajax.


5. Ques: What are the security issues with AJAX?
Answer:
The Ajax calls are sent in plain text format, this might lead to insecure database access. The data gets stored on the clients browser, thus making the data available to anyone. It also allows monitoring browsing sessions by inserting scripts.

AJAX function calls are sent in plain text to server. These calls may easily reveal database details, variable names etc