AJAX，作为答案获取对象

I have 2 php files: index and page. In index.php I write ajax/jquery code:

$(document).ready( function () {
        var mas;
        $.ajax({
            url: "page.php",
            type: "POST",
            data: "a=aaa&b=bbb",
            success: function (htm) {
                mas = htm;
                alert(htm);         
            }
        });


        $(document).on("click", function () {
            alert(mas['a']);
        });


    });

In page.php i have only this code:

 echo json_encode($_POST);

Data sends successfully, because I obtain in alert message: {"a":"aaa","b":"bbb"}. When I click on document, alerts : "undefined", please tell, where have I wrong? I want that alert "aaa"

The json_encode() function, does just that...encodes data as JSON. JSON is not a javascript object, it is notation for a javascript object. In order to use it as an object, you need to first parse it:

mas = JSON.parse(htm);

Then you can access values like:

alert(mas.a);

Add:

header('Content-type: application/json');

to the top of the PHP script.

Your JSON data is being treated as an HTML string and not inflated into a JavaScript object.

You need to tell jQuery to parse the JSON from the AJAX call. To do this add dataType: 'json' to $.ajax.

$.ajax({
    url: "page.php",
    type: "POST",
    data: "a=aaa&b=bbb",
    dataType: 'json',
    success: function (htm) {
        mas = htm;
        console.log(htm);         
    }
});