Javascript Object showing null

Question

I am trying to populate am empty object with data being returned from a POST request. The data is being returned successfully, but in the code the object is found to be null. The code is given below:

var item = {};   
var args= {p: "<?php echo $id; ?>"};

$.post('api.php', args, function(response) {

    startSpinner(spinner);
    if (response.status == 0) {
        item = response.data;
        console.log("ITEM: " + JSON.stringify(item));
    }

}).done(function() {
    ..
});

if (item == null || item == undefined) {
    alert("TTEMST");
}

In the console log, the item is clearly being shown to get populated with data, but the if condition for a null object is somehow being satisfied, i.e. the alert box is being displayed. I think there is something wrong with the way I am populating the object. Please help!!

score 2 · Accepted Answer · answered Nov 19 '15 at 15:43

2

$.post() is asynchronous. alert execute before your success callback

answered Nov 19 '15 at 15:43

gzc

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Thank you so much, I am still getting used to asynchronous execution! – user3033194 Nov 19 '15 at 15:45

score 1 · Answer 2 · answered Nov 19 '15 at 15:41

This line of code will most likely run before the post returns. You should add that to the callback or the then. The code will not wait for $.post to return before moving to that if statement.

if (item == null || item == undefined) {
    alert("TTEMST");
}

score 1 · Answer 3 · answered Nov 19 '15 at 15:42

Your if condition, which has alert won't wait for the Post to complete.

You need that if inside the callback of post, like this:

$.post('api.php', args, function(response) {

    startSpinner(spinner);
    if (response.status == 0) {
        item = response.data;
        console.log("ITEM: " + JSON.stringify(item));

        if (item == null || item == undefined) {
            alert("TTEMST");
        }
    }

Javascript Object showing null

3 Answers3