Getting to understand JavaScripts prototypal nature
Posted by fr3dr1k | Filed under AJAX, Web Technologies
One of the things that are quite weird to get use to, from a C# developer’s perspective, is JavaScript’s prototypical nature. Check out this basic example:
var objXMLHTTP =
{
getXMLHTTPObject: function(url,elementName) {
if (window.XMLHttpRequest) {
// code for IE7+, Firefox, Chrome, Opera, Safari
xmlhttp = new XMLHttpRequest();
}
else if (window.ActiveXObject) {
// code for IE6, IE5
xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
}
else {
alert("Your browser does not support XMLHTTP!");
}
xmlhttp.onreadystatechange = function() {
if (xmlhttp.readyState == 4) {
document.getElementById(elementName).innerHTML = xmlhttp.responseText;
}
}
xmlhttp.open("GET", url, true);
xmlhttp.send(null);
}
};
objXMLHTTP.getXMLHTTPObject("http://localhost/YieldTester/Handler.ashx", "testDiv");
The code above creates a simple XMLHTTPRequest object, but you do not create an instance of the object, you call it directly. Note objXMLHTTP.getXMLHTTPObject. In C# you might have created an object and then you instantiate it through an instance of that object. I have taken the code as is given on W3Schools and modified it a little.
