PHP + jQuery - undefined index: , but it still posts successfully?

Question

When inserting a record to a database, the server returns an 'undefined index: category', error, but still posts the successfully.

   $('#button').click(function(){
    var newvendor    = $('#input_vendor').val();
        newplantcode = $('#input_plantcode').val();
        newcategory  = $('#input_category').val();

$.post("php/addSite.php",
    {vendor: newvendor, 
     plant_code: newplantcode, 
     category: newcategory}, // <--- Error on this line, for some reason...


     function(result){
            console.log("server returned : " + result);
            [ RELOAD THE PAGE ]
     }

Answer 1

You having missing quote in almost all your code:

   $('#button').click(function(){
var newvendor    = $('#input_vendor').val();
var newplantcode = $('#input_plantcode').val();
var newcategory  = $('#input_category').val();

$.post("php/addSite.php",
{vendor: newvendor, 
 plant_code: newplantcode, 
category: newcategory}, // <--- Error on this line, for some reason...


 function(result){
        console.log("server returned : " + result);
        [ RELOAD THE PAGE ]
 }
 //closing the post function
 )
 //closing the click event 
 });

Now try that again