jQuery trigger change event doesn't work

Question

I'm having an issue with my JavaScript code, I want to fire a change event when I load the page, it used to work in local but now it's online and nothing happens.

Here's my code: (there's some php code, it works fine)

$("#city").change(function() {
    console.log("city changed...");
    var city = $( "#city option:selected" ).val();
    $.get(
        "ajax.php",
        {
            page: "venues",
            city: city
        },
        function (data) {
            $("#venue").empty();
            $("#venue").append('<option selected disabled>--</option>');
            for(var i = 0; i < data.venues.length; i+=1) {
                if (data.venues[i].id == <?php print $concert->getVenue()->getId(); ?>) {
                    $("#venue").append('<option value="'+data.venues[i].id+'" selected>'+data.venues[i].name+'</option>');
                } else {
                    $("#venue").append('<option value="'+data.venues[i].id+'">'+data.venues[i].name+'</option>');
                }
            }
            $("#label-venue").visible();
            $("#venue").visible();

            /*if (controlForm())
                $("#submit").removeProp("disabled");
            else
                $("#submit").addProp("disabled");*/
        }
    );
});

$("#country").change(function() {
    console.log("country changed...");
    var country = $( "#country option:selected" ).val();
    $("#country-city").html($( "#country option:selected" ).html());
    $.get(
        "ajax.php",
        {
            page: "cities",
            country: country
        },
        function (data) {
            $("#city").empty();
            $("#city").append('<option selected disabled>--</option>');
            $("#venue").empty();
            $("#venue").append('<option selected disabled>--</option>');
            for(var i = 0; i < data.cities.length; i+=1) {
                if (data.cities[i].id == <?php print $concert->getVenue()->getCity()->getId(); ?>) {
                    $("#city").append('<option value="'+data.cities[i].id+'" selected>'+data.cities[i].name+'</option>');
                } else {
                    $("#city").append('<option value="'+data.cities[i].id+'">'+data.cities[i].name+'</option>');
                }
            }
            $("#label-city").visible();
            $("#city").visible();
            $("#city").trigger("change");
        }
    );
});

function init() {
    $.get(
        "ajax.php",
        {
            page: "countries"
        },
        function (data) {
            $("#country").empty();
            $("#country").append('<option selected disabled>--</option>');
            for(var i = 0; i < data.countries.length; i+=1) {
                if (data.countries[i].id == <?php print $concert->getVenue()->getCity()->getCountry()->getId(); ?>) {
                    $("#country").append('<option value="'+data.countries[i].id+'" selected>'+data.countries[i].name+'</option>');
                } else {
                    $("#country").append('<option value="'+data.countries[i].id+'">'+data.countries[i].name+'</option>');
                }
            }
            $("#country").trigger("change");
        }
    );
}

$("#country-dismiss").click(function() {
    $("#country-name-en").val("");
    $("#country-name-nl").val("");
    $("#country-name-de").val("");
});

$("#city-dismiss").click(function() {
    $("#city-name-en").val("");
    $("#city-name-nl").val("");
    $("#city-name-de").val("");
});

$("#venue-dismiss").click(function() {
    $("#venue-name").val("");
    $("#venue-texte").val("");
    $("#venue-website").val("");
});

$("#country-submit").click(function() {
    console.log("adding country");
    var name_en = $("#country-name-en").val();
    var name_nl = $("#country-name-nl").val();
    var name_de = $("#country-name-de").val();

    $.post(
        "ajax.php?page=add_country",
        {
            en: name_en,
            nl: name_nl,
            de: name_de
        },
        function (data) {
            init();
            console.log(data);
        }
    );

});

$("#city-submit").click(function() {
    var name_en = $("#city-name-en").val();
    var name_nl = $("#city-name-nl").val();
    var name_de = $("#city-name-de").val();
    var country = $( "#country option:selected" ).val();

    $.post(
        "ajax.php?page=add_city",
        {
            country: country,
            en: name_en,
            nl: name_nl,
            de: name_de
        },
        function (data) {
            $("#country").trigger("change");
        }
    );
});

$("#venue-submit").click(function() {
    var name = $("#venue-name").val();
    var address = $("#venue-address").val();
    var website = $("#venue-website").val();
    var city = $( "#city option:selected" ).val();

    $.post(
        "ajax.php?page=add_venue",
        {
            city: city,
            name: name,
            address: address,
            website: website
        },
        function (data) {
            $("#city").trigger("change");
        }
    );
});

$( document ).ready(function() {
    (function($) {
        $.fn.invisible = function() {
            return this.each(function() {
                $(this).css("visibility", "hidden");
            });
        };
        $.fn.visible = function() {
            return this.each(function() {
                $(this).css("visibility", "visible");
            });
        };
    }(jQuery));
    init();
});

I hope someone will be able to see where I'm making a mistake (or several). Thanks!

Answer 1

You have to put your change events inside the callback function of $(document).ready(), anywhere before where you trigger them.

  $(document).ready(function(){ $(selector).change(function(){ ... }); $(selector).trigger("change"); //or $(selector).change(); }); 

I strongly recommend to never bind your selectors outside the ready event.

Answer 2

You could avoid the usage of $().trigger by defining the functions to be used as event handlers in the global namespace (or in a wrapper function if you're worried about adding properties to the global object).

Add the event handler by naming the funciton you defined, and when you need to trigger the event handler you just invoke that function.

I'll give you an example:

function countryChange () {
  ...
}

$('#country').on('change', countryChange);

function init() {
  ...
  countryChange(); 
}

$(document).ready(function () {
  init();
}

Answer 3

My problem got solved after I placed $(selector).trigger("change"); in $(document).ready() function. My whole document was being created by JS.

Answer 4

$( ".target" ).change(function() {
    alert( "Handler for .change() called." );
});