AJAX cached outcomes

Question

AJAX cached outcomes

Trying to educate myself on AJAX using w3schools.com, but struggling with a particular example:

xhttp.open("GET", "demo_get.asp", true);
xhttp.send();

In the above example, there might be a cached result. To prevent this, you can include a unique ID in the URL:

xhttp.open("GET", "demo_get.asp?t=" + Math.random(), true);
xhttp.send();

Query1: What exactly is a cached result and how does adding a unique ID to the URL help avoid it?

Query2: When we send data to a specific PHP file using GET Method, why do we need to use the $_REQUEST global variable instead of $_GET to retrieve the data from that file specifically?

Grateful for any insights or advice.

javascript php ajax caching

Answer 1

Answer №1

Web caching refers to the practice of storing files in the browser, which helps speed up browsing by eliminating the need to repeatedly fetch the same files.

1: Adding a random string or timestamp as a parameter tricks the browser into treating the file as new each time.

remotefile.js?ts=123 is considered different from remotefile remotefile.js?ts=124

2: In php 5.3+, data can be accessed by checking the global variables for the specific request type.

$_GET stores all get parameters (i.e., the part of the URL after ?)
$_POST contains an array of all POST parameters
file_get_contents('php://input') retrieves the json in a json-request

The reason why $_GET does not display attached GET-data is because a GET request only deals with URL parameters. For sending data, consider using POST instead.

http://www.w3schools.com/jquery/ajax_post.asp

Answer 2

Web caching refers to the practice of storing files in the browser, which helps speed up browsing by eliminating the need to repeatedly fetch the same files.

1: Adding a random string or timestamp as a parameter tricks the browser into treating the file as new each time.

remotefile.js?ts=123 is considered different from remotefile remotefile.js?ts=124

2: In php 5.3+, data can be accessed by checking the global variables for the specific request type.

$_GET stores all get parameters (i.e., the part of the URL after ?)
$_POST contains an array of all POST parameters
file_get_contents('php://input') retrieves the json in a json-request

The reason why $_GET does not display attached GET-data is because a GET request only deals with URL parameters. For sending data, consider using POST instead.

http://www.w3schools.com/jquery/ajax_post.asp

Answer 3

Answer №2

Query 1 :

Cached Result:
- Who Does the Caching? Browser
- What Gets Cached? : For each request (URL), the browser caches the response (result)
- Where is it Cached? Temporary memory of the Browser (in the HDD of the computer)
```
"demo_get.asp?t=" + Math.random()
```
:

This will alter the URL for every call, so, for instance, if demo_get.asp?t=32332 is cached, it will not affect demo_get.asp?t=43948348. Thanks to Math.random()

Query 2:

Based on the Method utilized on the client side, you can manage requests on the server-side effectively.

GET Method:

   //client side 
    xhttp.open("GET", "demo_get.asp?t=" + Math.random(), true);
  //server side 
     $_GET

POST Method:

   //client side 
     xhttp.open("POST", "demo_get.asp?t=" + Math.random(), true);
   //server side 
     $_POST

Answer 4

Query 1 :

Cached Result:
- Who Does the Caching? Browser
- What Gets Cached? : For each request (URL), the browser caches the response (result)
- Where is it Cached? Temporary memory of the Browser (in the HDD of the computer)
```
"demo_get.asp?t=" + Math.random()
```
:

This will alter the URL for every call, so, for instance, if demo_get.asp?t=32332 is cached, it will not affect demo_get.asp?t=43948348. Thanks to Math.random()

Query 2:

Based on the Method utilized on the client side, you can manage requests on the server-side effectively.

GET Method:

   //client side 
    xhttp.open("GET", "demo_get.asp?t=" + Math.random(), true);
  //server side 
     $_GET

POST Method:

   //client side 
     xhttp.open("POST", "demo_get.asp?t=" + Math.random(), true);
   //server side 
     $_POST

Answer 5

Answer №3

QUERY 1 When talking about cached results, it refers to the concept of storing the response fetched by the XMLHttpRequest object in your browser for a temporary period. This implies that upon requesting a response again, you will receive the previous (cached) response unless a different id is used compared to the one associated with the cached response. Essentially, utilizing unique ids guarantees accessing the specific file from which data is being retrieved whenever a response is requested.

Answer 6

QUERY 1 When talking about cached results, it refers to the concept of storing the response fetched by the XMLHttpRequest object in your browser for a temporary period. This implies that upon requesting a response again, you will receive the previous (cached) response unless a different id is used compared to the one associated with the cached response. Essentially, utilizing unique ids guarantees accessing the specific file from which data is being retrieved whenever a response is requested.

AJAX cached outcomes

Answer №1

Answer №2

Query 1 :

Query 2:

Answer №3

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