Can you offer guidance on how to correctly execute an AJAX request?

Question

Can you offer guidance on how to correctly execute an AJAX request?

I am currently facing a challenge with my JavaScript function, as I need it to call a PHP function and return either true or false.

The script containing the function is located in /db/cancel_hike.php

Here is a snippet of my existing JS:

function uncancelHike( hike_id )
{
    //var url = "/db/cancel_hike.php;
    var success = null;

    var request = window.ActiveXObject ?
          new ActiveXObject('Microsoft.XMLHTTP') :
          new XMLHttpRequest;

    request.open("GET", url , true);

    request.onreadystatechange = function()
    {
          if (request.readyState == 4)
          {
                var xmlDoc = request.responseXML;

                // obtain the array of markers and loop through it
                markers = xmlDoc.documentElement.getElementsByTagName("marker");

                for (var i = 0; i < markers.length; i++)
                {
                      // obtain the attribues of each marker
                      success = markers[i].getAttribute("success");

                      if ( success == "true" )
                      {
                        document.getElementById("success").style.display = 'block';
                        document.getElementById("warning").style.display = 'none';
                        document.getElementById("error").style.display = 'error';

                      }

                      if ( success == "false" )
                      {
                        document.getElementById("success").style.display = 'none';
                        document.getElementById("warning").style.display = 'none';
                        document.getElementById("error").style.display = 'block';
                      }
                }
          }
    }

    request.send(null);

    return false;
}

Some questions that have arisen are:

How can I effectively call an actual function in the PHP script?
Is it mandatory to have XML returned? Or is there a way to receive only the returned value?
As I am using the YUI JS library, should I make specific calls to it or is it unnecessary in this scenario?

javascript ajax yui

Answer 1

Answer №1

What is the method for invoking a function within a PHP script?

In PHP, functions are not directly called; instead, URIs are requested.

To execute a specific function in PHP, you need to create a script that contains the function and then access it through the designated URI.

(One way to achieve this is by using query strings as inputs for conditional statements that determine which function to call)

Is it required for the output to be in XML format, or can I just receive the returned value directly?

In PHP, you have the flexibility to return any type of data you prefer.

If I am utilizing the YUI JS library, do I have to make specific calls to it, or is it optional in this scenario?

The YUI JS library serves as a tool to simplify coding tasks; making calls to it is not mandatory but can streamline your development process.

Answer 2

What is the method for invoking a function within a PHP script?

In PHP, functions are not directly called; instead, URIs are requested.

To execute a specific function in PHP, you need to create a script that contains the function and then access it through the designated URI.

(One way to achieve this is by using query strings as inputs for conditional statements that determine which function to call)

Is it required for the output to be in XML format, or can I just receive the returned value directly?

In PHP, you have the flexibility to return any type of data you prefer.

If I am utilizing the YUI JS library, do I have to make specific calls to it, or is it optional in this scenario?

The YUI JS library serves as a tool to simplify coding tasks; making calls to it is not mandatory but can streamline your development process.

Answer 3

Answer №2

How can I execute a function in a PHP script?

Is it necessary to receive XML data, or can I just retrieve the returned value?

In PHP, you don't directly call a function. Instead, you pass variables through GET by appending them to the URL like

file_name.php?var1=this&var2=that

. These variables are then retrieved in the PHP file using $_GET['this'] and $_GET['that']. Any output from PHP using echo, print_r, etc. is sent back in the responseText property of a request object.

To make a request, set the url in request.open to a URL on your site. For example, in a .js file:

request.open("GET", "answer_me.php?hike_id=" + hike_id, true);

And in a .php file:

<?php
$hike_id = $_GET['hike_id'];
if ($hike_id < 5) {
  echo "true";
} else {
  echo "false";
}

This will return a string value to request.responseText. Based on this response, you can perform actions such as displaying success or error messages using JavaScript.

You do not necessarily need to format the response as XML if you are not utilizing a loop or multiple DOM elements.

For AJAX functionality, using frameworks like jQuery can simplify your code considerably. Here is an example using jQuery:

var $success = $("#success");
var $error = $("#error");

function cancelHikeCallback(data) {
  var is_success = (data === "true");
  $success.toggle(is_success);
  $error.toggle(!is_success);
}

function cancelHike(hikeIdToSend) {
  $.get("/db/cancel_hike.php", {hike_id: hikeIdToSend}, cancelHikeCallback);
}

jQuery's AJAX methods like $.ajax and $.get provide a more concise and readable way to handle asynchronous requests.

View a jsFiddle Example

Answer 4

How can I execute a function in a PHP script?

Is it necessary to receive XML data, or can I just retrieve the returned value?

In PHP, you don't directly call a function. Instead, you pass variables through GET by appending them to the URL like

file_name.php?var1=this&var2=that

. These variables are then retrieved in the PHP file using $_GET['this'] and $_GET['that']. Any output from PHP using echo, print_r, etc. is sent back in the responseText property of a request object.

To make a request, set the url in request.open to a URL on your site. For example, in a .js file:

request.open("GET", "answer_me.php?hike_id=" + hike_id, true);

And in a .php file:

<?php
$hike_id = $_GET['hike_id'];
if ($hike_id < 5) {
  echo "true";
} else {
  echo "false";
}

This will return a string value to request.responseText. Based on this response, you can perform actions such as displaying success or error messages using JavaScript.

You do not necessarily need to format the response as XML if you are not utilizing a loop or multiple DOM elements.

For AJAX functionality, using frameworks like jQuery can simplify your code considerably. Here is an example using jQuery:

var $success = $("#success");
var $error = $("#error");

function cancelHikeCallback(data) {
  var is_success = (data === "true");
  $success.toggle(is_success);
  $error.toggle(!is_success);
}

function cancelHike(hikeIdToSend) {
  $.get("/db/cancel_hike.php", {hike_id: hikeIdToSend}, cancelHikeCallback);
}

jQuery's AJAX methods like $.ajax and $.get provide a more concise and readable way to handle asynchronous requests.

View a jsFiddle Example

Can you offer guidance on how to correctly execute an AJAX request?

Answer №1

Answer №2

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