Part 1: jQuery -> MySQL -> jQuery -> HTML

Question

I'm developing an application which relies heavily on jQuery for user interaction.
(and if you're browser doesn't support jQuery, then upgrade or don't use my application :)

As normal, one have functions to GET, SET and DELETE data from a table.

In my application, I'm GET'ing and SET'ing a lot of information without page reload. To do this, I mostly use jQuery.post.

A typical code in my JS file looks like this:

jQuery.post("mypath/jquery_getset_data.php", { instance: 'getItems_A', itemID: itemID_value},
  function(data) {
    populateItemList(data);
  }); 

The jquery_getset_data.php contains of many if statements:

if($_POST['instance'] == 'getItems_A'){
  // PHP code to get and process data from MySQL DB
}

if($_POST['instance'] == 'setItems_A'){
  // PHP code to process and insert data to MySQL DB
}

Here's my question:

1. Is tehre a better way for interaction between JS file and jquery_getset_data.php?

2. How can I dynamically call different "remove item" functions inside createStoreList? See update 1.

Update 1: This is the code that I use to create many different lists.

  function createStoreList(data)
  {
    var ul = jQuery("<ul/>");

    // We need to build the html structure in order for this to be registered in DOM.
    // If we don't, jQuery events like .click, .change etc. will not work.      
    for (var i = 0; i < data.length; i++)  
    {
      ul.append(
         jQuery("<li/>")
         .attr("id", "listItem_"+data[i].id)
         .append(jQuery("<span/>")
            .addClass("btnRemoveItem")
            .attr("title", "Remove store from list")
            .attr("id", data[i].id)
            .click(function() { removeItemA(this); })  
          )
         .append(data[i].name + ', ' + data[i].street)
        );              
    }
    return ul;  
  }

Update 2 I figured I just could use switch statements. I've tested it and it works.

    .click(function() {
        switch(instance)
        {
          case 'removeListItemA': removeListItemA(this); break; 
          case 'removeListItemA': removeListItemB(this); break;
          case 'removeListItemA': removeListItemC(this); break;
        }
    })

Answer 1

The only thing I would change is in jquery_getset_data.php I would use a switch statement instead of many if statements. jQuery's $.post method is fine for what you're doing, talking to a script that affects the database (deletes/updates/etc) using one of the GET ajax methods ($.load or $.get) breaks the HTTP specification.

Answer 2

In order to reduce the jquery_getset_data.php I would use the OOP design patterns to avoid switches and if statements.

class ICommand
{
     public:
          function execute( );
};

class CommandGetItemA
{
     public:
           function execute( )
           {
               //do some staff here
           };
};

and then:

CommandsMap['getItemA'] = new CommandGetItemA( );
CommandsMap['setItemA'] = new CommandGetItemB( );
....

CommandsMap[ $_POST['instance']].execute( );

I know looks complicated, but for my taste looks much better. And regarding your second question I'm not sure I understood it, can you add more explanation?

After I saw you update, I think for second question you can do:

.click(function() {
      window[instance]( this);   
});

There the "instance" is the function name, or you can update or append it latter to make it be the function name;