Question

Hi this is an example of the code i want to run:

        $('#search1').submit(function(){
    var date = $('#date').val();
    var location = $('#location').val();
    var datastring = 'date=' + date + '&location=' + location;
    $.ajax({
        type: "POST",
        cache: "true",
        url: "search.php",
        dataType:"json",
        data: datastring,
        success: function(data){
            $('#main').html('')
            for ($i = 0, $j = data.bus.length; $i < $j; $i++) {

                //Create an object for each successful query result that holds information such as departure time, location, seats open...

                   $('#main').append(html);

            }

How would I go about coding the success function? I want the object to store each bus’ information so that the info can be displayed in the search result as well as being able to be referenced when the user confirms his RSVP later on. Thanks ahead of time

Answer 1

You can declare an object to use as a map in the containing scope:

var busInfo = {};

…and then if the bus entries have some form of unique identifier, you can record them like this:

success: function(data){
    var $i, $j, bus;

    $('#main').html('')
    for ($i = 0, $j = data.bus.length; $i < $j; $i++) {
        // Remember this bus by ID
        bus = data.bus[$i];
        busInfo[bus.id] = bus;

        $('#main').append(html);
    }
}

And then later, when the user chooses a bus, use the chosen ID to get the full bus information:

var bus = busInfo[theChosenId];

This works because all JavaScript objects are key/value maps. Keys are always strings, but the interpreter will happily make strings out of what you give it (e.g., busInfo[42] = ... will work, 42 will become "42" implicitly).

If you just want an array, your data.bus already is one, right?

var busInfo = [];

// ....

success: function(data){
    var $i, $j;

    // Remember it
    busInfo = data.bus;

    $('#main').html('')
    for ($i = 0, $j = data.bus.length; $i < $j; $i++) {

        $('#main').append(html);
    }
}

(Note that JavaScript arrays aren’t really arrays, they too are name/value maps.)

---

Update: I dashed off a quick example of the keyed object (live copy):

HTML:

<input type='button' id='btnLoad' value='Load Buses'>
<br>...and then click a bus below:
<ul id="busList"></ul>
...to see details here:
<table style="border: 1px solid #aaa;">
  <tbody>
    <tr>
      <th>ID:</th>
      <td id="busId">--</td>
    </tr>
    <tr>
      <th>Name:</th>
      <td id="busName">--</td>
    </tr>
    <tr>
      <th>Route:</th>
      <td id="busRoute">--</td>
    </tr>
  </tbody>
</table>

JavaScript with jQuery:

jQuery(function($) {
  // Our bus information -- note that it's within a function,
  // not at global scope. Global scope is *way* too crowded.
  var busInfo = {};

  // Load the buses on click
  $("#btnLoad").click(function() {
    $.ajax({
      url: "http://jsbin.com/ulawem",
      dataType: "json",
      success: function(data) {
        var busList = $("#busList");

        // Clear old bus info
        busInfo = {};

        // Show and remember the buses
        if (!data.buses) {
          display("Invalid bus information received");
        }
        else {
          $.each(data.buses, function(index, bus) {
            // Remember this bus
            busInfo[bus.id] = bus;

            // Show it
            $("<li class='businfo'>")
              .text(bus.name)
              .attr("data-id", bus.id)
              .appendTo(busList);
          });
        }
      },
      error: function() {
        display("Error loading bus information");
      }
    });
  });

  // When the user clicks a bus in the list, show its deatils
  $("#busList").delegate(".businfo", "click", function() {
    var id = $(this).attr("data-id"),
        bus = id ? busInfo[id] : null;
    if (id) {
      if (bus) {
        $("#busId").text(bus.id);
        $("#busName").text(bus.name);
        $("#busRoute").text(bus.route);
      }
      else {
        $("#busId, #busName, #busRoute").text("--");
      }
    }
  });

});

Data:

{"buses": [
    {"id": 42, "name": "Number 42", "route": "Highgate to Wycombe"},
    {"id": 67, "name": "Old Coach Express", "route": "There and Back"}
]}

---

Off-topic: Note that I’ve added var $i, $j; to your success function. Without it, you’re falling prey to The Horror of Implicit Globals, which you can tell from the name is a Bad Thing^(tm).