Check for username while typing in field? - php

Question

I am fluent with HTML, and mostly PHP.
I can do the scanning part with PHP.. I'm just not sure how to call a function in PHP with JavaScript, because I don't know JavaScript.
My PHP code will connect to my MySQL database and see if the text currently in the textbox (Not clicked enter yet, still typing) is in the database..
Do you know how to do this, or at least know a link that tells you how to do it?

Answer 1

This sounds like a problem for jQuery. I'd give you a long-winded example, but there are many people that would give you a much better one: like this guy.

Answer 2

Consider using jQuery in conjunction with jQuery UI, specifically something called autocomplete. I'm fairly certain it does what you're wanting, and it's completely themable for your site.

Answer 3

I see everybody likes jQuery so much, wow!
I'd tell you just need some very basic Ajax script to call your PHP script and receive the response.
Here's the simple Javascript function (actually two):
function getXMLObject() {
var xmlHttp = false;
try {
xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");// For Old Microsoft Browsers
}
catch (e) {
try {
xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");// For Microsoft IE 6.0+
}
catch (e2) {
xmlHttp = false;// No Browser accepts the XMLHTTP Object then false
}
}
if (!xmlHttp && typeof XMLHttpRequest != 'undefined') {
xmlHttp = new XMLHttpRequest();//For Mozilla, Opera Browsers
}
return xmlHttp;// Mandatory Statement returning the ajax object created
}
var xmlhttp = new getXMLObject();//xmlhttp holds the ajax object
//use this method for asynchronous communication
function doRequest(scriptAddressWithParams, callback) {
if (xmlhttp) {
xmlhttp.open("POST", scriptAddressWithParams, true);
xmlhttp.onreadystatechange = function () {
if (xmlhttp.readyState == 4) {
if (xmlhttp.status == 200) {
callback(xmlhttp.responseText);
}
else {
alert("Error retrieving information (status = " + xmlhttp.status + ")\n" + response);
}
}
};
xmlhttp.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
xmlhttp.send(null);
}
}
and here's an example of usage:
<input type="text" onchange="doRequest('myphpscript.php?checkvalue='+this.value, function (returnedText) { alert(returnedText);});"/>