I am doing some experiments with AJAX calls in pure Javascript, no JQuery. I wonder if I can populate a DIV tag like this:
<script type="text/javascript">
function call_test() {
document.getElementById("myId").innerHTML = ajax_call("example.php?id=1") ;
}
</script>
<body>
<input type="button" onClick="call_test()" value"Test">
<div id="myId">Result should be here</div>
The problem is how to return the result from ajax_call? My code is as follows, but not working:
function ajax_call(remote_file)
{
var $http,
$self = arguments.callee ;
if (window.XMLHttpRequest) {
$http = new XMLHttpRequest();
} else if (window.ActiveXObject) {
try {
$http = new ActiveXObject('Msxml2.XMLHTTP');
} catch(e) {
$http = new ActiveXObject('Microsoft.XMLHTTP');
}
}
if ($http) {
$http.onreadystatechange = function() {
if (/4|^complete$/.test($http.readyState)) {
return http.responseText ; // This only return undefined
}
};
$http.open('GET', remote_file , true);
$http.send(null);
}
}
Remote file:
<?php
echo "<h1>Jus an experiment</h1>";
?>
It will not work because of the asynchronous nature of AJAX requests. The ajax_call method will return before the server responds with the html that is why you are getting undefied.
The solution here is to use a callback to do the post processing of ajax response as shown below.
function ajax_call(remote_file, callback) {
var $http, $self = arguments.callee;
if (window.XMLHttpRequest) {
$http = new XMLHttpRequest();
} else if (window.ActiveXObject) {
try {
$http = new ActiveXObject('Msxml2.XMLHTTP');
} catch (e) {
$http = new ActiveXObject('Microsoft.XMLHTTP');
}
}
if ($http) {
$http.onreadystatechange = function() {
if (/4|^complete$/.test($http.readyState)) {
if (callback)
callback(http.responseText);
}
};
$http.open('GET', remote_file, true);
$http.send(null);
}
}
And
function call_test() {
ajax_call("example.php?id=1", function(html) {
document.getElementById("myId").innerHTML = html
});
}