在jQuery / javascript中定义全局变量

Question

Defining a Global variable in JavaScript/jQuery and getting it later in script.

But strange it is not working.

printing getResult in console giving me undefined .

but when trying to print getResult just after the assigned value to it, it is giving me accurate value.

Actually i need ajax result at the bottom .. how could i do this..?

var getResult;
$.getJSON(url, function(data) {
    //JS statement to Ajax
    //JS statement to Ajax  
    $.ajax({
        type: "post",
        dataType: "json",
        url: urlTo,
        data: dataSend,
        success: function (result, status) {
                getResult = result; 
                console.log(getResult); // getResult is working here
        }
    });

    //JS statement to Ajax
    //JS statement to Ajax  
    $.ajax({
        type: "post",
        dataType: "json",
        url: urlTo2,
        data: dataSend2,
        success: function (result2, status) {

        }
    });

    console.log(getResult); // getResult is not working here. Giving " undefined" result here.
});

Answer 1

JavaScript is synchronous . AJAX is asynchronous .

Therefore, the console.log(getResult); at the bottom is firing before the following AJAX executes:

success: function (result, status) {
    getResult = result; 
    console.log(getResult); // getResult is working here
} 

You can give getResult a default value and test it yourself.

Answer 2

That is because getResult is not defined until the AJAX call is done, it is only declared .

Since AJAX is async, your first console log is like that :

var getResult;
console.log(getResult);

Can you give me the value of getResult here? No, because it is undefined (well actually its value is undefined , shhh )

Answer 3

On the second AJAX call, you did not assign getResult = result2; causing "undefined" value.

Also, put the global var = getResult; inside the getJSON function.