Question

I want to create a Login-Screen in HTML where the user can fill out his username and password. After that he sends the Data with a submit to the server which validate the data. If the Login is correct he sends back a message in JSON format with an id, like this:

{"id":"37"}

Now my question: How can i get this information in Javascript? I want to check the id and, if it’s OK, redirect the user to a new HTML screen.

I’m working with PhoneGap to create a Android Application, so the only things I can use are HTML, CSS and JavaScript. To send the POST i use the HTML <form> tag, not a special JavaScript. If I test it in Firefox it works, I fill out my Username and Password and then the Message with the id is shown. Now I want to react on this response with JavaScript. Can somebody help me?

AJAX Code:

function loadXMLDoc() {
    var xmlhttp;
    if (window.XMLHttpRequest) {
        // code for IE7+, Firefox, Chrome, Opera, Safari
        xmlhttp=new XMLHttpRequest();
    }
    else {
        // code for IE6, IE5
        xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
    }
    xmlhttp.onreadystatechange = function() {
        if (xmlhttp.readyState==4) {
            document.getElementById("myDiv").innerHTML=xmlhttp.responseText;
        }
    };
    xmlhttp.open("POST",url,true);
    xmlhttp.send(login);

Answer 1

A JSON parser will recognize only JSON text, rejecting all scripts. In browsers that provide native JSON support, JSON parsers are also much faster than eval. It is expected that native JSON support will be included in the next ECMAScript standard.

var myObject = JSON.parse(myJSONtext, reviver);

The optional reviver parameter is a function that will be called for every key and value at every level of the final result.

now access the id property like myObject.id