Question

Make jQuery elements execute after they been loaded in (after finish page-load)

Answer 1

events may be triggered. When you use an additional custom event for initializing, e.g. “reload”:

/*! -- ui-slider -- */ 

$(document).on('ready reload',function() {
        $( "#slider" ).slider({
            range: true,
            min: 0,
            max: 500,
            values: [ 25, 450 ],
            slide: function( event, ui ) {
                $( "#value" ).val( "" + ui.values[ 0 ] + " - " + ui.values[ 1 ] );
            }
        });
        $( "#value" ).val( "" + $( "#slider" ).slider( "values", 0 ) +
            " - " + $( "#slider" ).slider( "values", 1 ) );
    });

/*! -- toggleclass -- */

$(document).on('ready reload',function() {
    $("#div3").on('click', '.toggle', function () {
        $(this).toggleClass("toggle_background");
    });
});

….then you only need to trigger the reload-event inside the callback of $.load()

$(document).ready(function(){ 
$("#selectbox").change(function(){ 
    var selectedOption = $('#selectbox :selected').val(); 
    $containerDiv = $('#receive_content'); 
    $containerDiv.html("");
        switch (selectedOption)
        {
     case "Selectbox":$containerDiv.load( "default" ,
                                  function(){$(document).trigger('reload');} );
                                      break;

     case "Option 1":$containerDiv.load( "content.html #div1" ,
                                  function(){$(document).trigger('reload');});
                                      break;

     case "Option 2":$containerDiv.load( "content.html #div2" ,
                                  function(){$(document).trigger('reload');});
                                      break;

     case "Option 3":$containerDiv.load( "content.html #div3" ,
                                  function(){$(document).trigger('reload');});
                                      break;        
       }
    return true;
    }); 
});