XMLHttpRequest Object

[yngjzy12]

Hey everyone, I'm new to this forum but hopefully someone can help out. My questions concerns the XMLHttpRequest object. I'm creating a web app that is suppose to emulate a MS Access database. The idea is to automatically update input text boxes when the user changes their value, among other things. At this point, I'm creating a new XMLHttpRequest object each time the onblur method is called on a textbox and sending the info to a php page and updating it accordingly. My question is will creating a new XMLHttpRequest object each time cause problems within the Javascript or browser? Also, it seems if I just create one instance of the XMLHttpRequest object and try to re-use it, in IE things don't work. Any ideas on why this happens? I hope this is a clear explanation, and thanks for any help.

 

[dwarfthrower]

My question is will creating a new XMLHttpRequest object each time cause problems within the Javascript or browser?

Creating a lot of them in a short space of time can cause a bit of a slow down, but so can creating a whole bunch of strings. Creating a new XMLHttpRequest every time a user selects an option in a couple of comboboxes shouldn't pose a problem on any modern computer.

Also, it seems if I just create one instance of the XMLHttpRequest object and try to re-use it, in IE things don't work. Any ideas on why this happens?

My thoughts would be that you're having one bit of code modify a global variable while another bit of code hasn't finished with it yet. Either that or you've got scope issues.

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[yngjzy12]

Thanks for the reply. I actually came up with an article with an explanation of the issue I was referring to with IE not being able to re-use an XMLHttpRequest Object. It turns out that you need to call the open method before you assign the onreadystate callback handler. The article is here:

http://keelypavan.blogspot.com/2006/03/reusing-xmlhttprequest-object-in-ie.html

Thanks again