How to make Ajax work for you

How to make Ajax work for you » SlideShare – simple & clear AJAX codes
How to make Ajax work for you

var xhr = createXHR();xhr.onreadystatechange = function() {    if (xhr.readyState == 4) {        if (xhr.status == 200) {            alert(xhr.responseText);        } else {            alert('Error code ' + xhr.status);        }    }};xhr.open('GET', '/helloworld.txt', true);xhr.send(null);

function createXHR() {    var xhr = null;    if (window.XMLHttpRequest) {        xhr = new XMLHttpRequest();    } else if (window.ActiveXObject) {        try {            xhr = new ActiveXObject('Microsoft.XMLHTTP');        } catch (e) {}    }    return xhr;}

var xhr = createXHR();xhr.onreadystatechange = onComplete;xhr.open('POST', '/helloworld.php', true);xhr.setRequestHeader(    'Content-Type',    'application/x-www-form-urlencoded');xhr.send('name=Simon&age=26');

xhr.open(‘POST’, ‘/helloworld.php’, true);
The third argument specifies that we want to make an asynchronous request (“tell me when you’re done by calling this function”). If you set this to false you’ll get a synchronous request, which will completely hang the browser until the request returns. Don’t do that.

function buildQueryString(obj) {    var bits = [];    for (var key in obj) {        if (obj.hasOwnProperty(key)) {            bits[bits.length] = escape(key) + '=' +            escape(obj[key]);        }    }    return bits.join('&');}var s = buildQueryString({    name: 'Simon',    age: 26});name=Simon&age=26

There’s still a complete doRequest function. Keep reading …

<form id="evil" action="http://example.com/admin/delete.php" method="POST">    <input type="hidden" name="id" value="5"></form><script>document.getElementById('evil').submit()</script>