Question

Before I perform some json and disable a button, I simply want to enable other buttons that may have been previously disabled. I think it’s related to callbacks which I apparently still don’t get. In the code below, the clicked button does not become disabled prior to running the getJSON.

$(".btnUseProduct").live("click", function(e) {

    var clickedId = $(this).attr('id');
    var provisioning_id = clickedId.split("^")[0];
    var entity_id = clickedId.split("^")[1];
    var entity = clickedId.split("^")[2];

    showUseButtons(function(){        

               $(this).attr({'disabled':'disabled','value':'Used'}); //doesn't work
               $.getJSON("/chinabuy-new/cfcs/services.cfc?method=update_provisioning&returnformat=json&queryformat=column",{"provisioning_id":provisioning_id,"entity_id":entity_id},function(res,code){                        
               });
        });
    e.preventDefault();
});

function showUseButtons() {
    $(".btnUseProduct").each(function(e) {
        $(this).attr({'disabled':'disabled','value':'Used'});
    });
}       

Answer 1

A callback is a function you pass to another function. That other function you pass it to must call it – otherwise it’s useless.

function someFunctionThatCallsBack(someCallbackFunction) {
  // do something
  someCallbackFunction(); // calls the callback function
}

Above, you are passing a function to showUseButtons – but that function just ignores it. It won’t be called so whatever you put in there won’t do anything.

Perhaps you meant something like the following?

function showUseButtons(callback) {
    $(".btnUseProduct").each(function(e) {
        $(this).attr({disabled: true, value:'Used'});
    });
    callback();
}       

Further, inside a function the context changes (i.e. the value of this is different). So you’ll need to alter your code somewhat as well:

    var _this = this; // save the context - the clicked DOM element
    showUseButtons(function(){        
           $(_this).attr({disabled:true, value:'Used'}); //doesn't work
           $.getJSON("/chinabuy-new/cfcs/services.cfc?method=update_provisioning&returnformat=json&queryformat=column",{"provisioning_id":provisioning_id,"entity_id":entity_id},function(res,code){                        
           });
    });