Why is this POST variable sent via AJAX Null? (jquery/php)

Question

This javascript is for a "load more" functionality. That grabs a fixed number of elements from load.php when a button #moreg is clicked.

$(function(){
    $("#moreg").click(load);
    var countg = -1;
    load();


    function load() {
        var num = 1;
        countg += num;
        $.post( "load.php", 
                {'start_g': 'countg', 'name':'<?=$name?>' }, 
                function(data){
                    $("#posts").append(data);
                }
        );
    }
});

in load.php simply doing a var_dump($_POST['start_g']); yields a null variable.

Not too helpful...what am I doing wrong?

Your example should work, var_dump should return the string 'count_g'. Try clearing the cache. — Dr.Molle
– Dr.Molle, Commented Oct 8, 2011 at 23:29
@James Allardice: Undelete your answer, the quotes on the value were the problem, the quotes on the keys was just a side issue. — mu is too short
– mu is too short, Commented Oct 8, 2011 at 23:47

James Allardice · Accepted Answer · 2011-10-08 23:31:28Z

2

In the map of parameters that get sent with the POST request, the keys do not have to be quoted (but it doesn't make any difference):

$.post("load.php", {
    start_g: countg, 
    name: '<?=$name?>' 
}, function(data) {
    $("#posts").append(data);
});

And I've also removed the quotes from countg, because you're trying to use the value of a variable. If it's quoted, you're simply going to pass the string "countg" rather than the value of the variable named countg.

edited Oct 8, 2011 at 23:31

answered Oct 8, 2011 at 23:25

James Allardice

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2 Comments

James Allardice Over a year ago

Yeah, you're right. I was just about to edit. In fact, in some cases, quotes are required (I don't think the underscore is one of those cases though). In fact that means my answer is completely wrong... $_POST["start_g"] should contain "countg", and definitely should not be null. Deleting...

algorithmicCoder Over a year ago

yeah not sure why it was returning null...but removing the quotes around it fixed the problem...odd..i must have had something else that was wrong that got fixed.

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