Inconsistencies with AJAX performance

Hey there, I'm a newbie and absolutely loving this site!

Currently diving into the world of JavaScript and have been through numerous tutorials. However, I seem to be struggling with getting Ajax to work.

Recently stumbled upon this code snippet on W3school:

   var xmlhttp;
if (window.XMLHttpRequest)
  {// code for IE7+, Firefox, Chrome, Opera, Safari
  xmlhttp=new XMLHttpRequest();
  }
else
  {// code for IE6, IE5
  xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
  }
xmlhttp.onreadystatechange=function()
  {
  if (xmlhttp.readyState==4 && xmlhttp.status==200)
    {
    document.getElementById("myDiv").innerHTML=xmlhttp.responseText;
    }
  }
xmlhttp.open("GET","ajax_info.txt",true);
xmlhttp.send();

Decided to tweak it by altering one line to:

xmlhttp.open("GET","ajax_info.php?day="+document.getElementById("day").value,true);

This change aims at fetching information specific to a certain day instead of all days.

Encountering a peculiar scenario where sometimes the page goes blank, glitches out, but then magically works fine on other occasions.

To replicate the issue, simply hit F5 three times consecutively - chances are, it will fail atleast once.

In desperate need of some guidance here before I lose the few hair strands left on my head! Please assist!

Answer №1

The issue arises from the script loading too quickly, causing the "day" element to not yet be present.

To resolve this, you can add an event handler to wait for the document to fully load.

You can achieve this by using:

document.addEventListener("load", functionName, false);
and then creating a function to contain the provided code snippet.

By doing so, the function will be executed at the appropriate time and should address the problem.

In addition, it is advisable to utilize libraries such as jQuery or MooTools to facilitate cross-browser compatibility for your code. In your current implementation, you are checking for the user's browser in order to initiate the request.

jQuery simplifies this process with just one line of code:

$(document).ready(function(){   // Wait for the document to load
    $.get("http://www.website.com?day="+$("#day").val());   // $.get initiates an ajax request, $("#day") retrieves an element by its Id
});

For further information, visit

Answer №2

Hey @Karmen, I didn't get to see your full code so it's hard to know why it might be failing. I ran multiple refreshes on my test page located at , and did not encounter any issues even after refreshing more than 10 times.

Just a friendly reminder to make sure to give the page enough time to fully load each time since connection speeds can vary.

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