If statement doesn't work / Javascript / Jquery

Question

I don't why my website doesn't go through the if statement. The objective is to display an image when I click a button, but it gets stuck. If anyone could help I would be very happy :D

function showllum() {
        $.get('llum.txt', function(data) {
            alert(data);
            if (data === "Llum") {
                    alert("1");
                    $('#showdada').empty();
                    $('#showdada').prepend($('<img>', {
                            id: 'llumpng',
                            src: 'llum.png'
                        }

                    ))
            } else if (data === "Molta Llum") {
                    alert("2");
                    $('#showdada').empty();
                    $('#showdada').prepend($('<img>', {
                            id: 'moltallumpng',
                            src: 'molta llum.png'
                        }

                    ))

                } else if (data === "Poca Llum") {
                        alert("3");
                        $('#showdada').empty();
                        $('#showdada').prepend($('<img>', {
                                id: 'pocallumpng',
                                src: 'poca llum.png'
                            }

                        ))

                    } else if (data === "Fosques") {
                            alert("4");
                            $('#showdada').empty();
                            $('#showdada').prepend($('<img>', {
                                    id: 'fosquespng',
                                    src: 'fosques.png'
                                }

                            ))

                        }})}

Answer 1

In addition to the carriage return in the string that was causing the original problem (which is fixed with data.trim()), your code can be simplified since there's a pattern to your logic - each case clears the showdada element and then prepends an image using the pattern src = `${data.trim()}.png` in lowercase and then the id removes all spaces and periods from the src:

function showllum() {
  $.get('llum.txt', function(data) {
    $('#showdada').empty();
    const src = `${data.trim()}.png`.toLowerCase();
    $('#showdada').prepend($('<img>', {
      id: src.replace(/[ .]/g,''),
      src
    })
  });
}

Answer 2

You need to add a dataType - http://api.jquery.com/jQuery.ajax/

$(document).ready(function() {
    $.ajax({
        url : "helloworld.txt",
        dataType: "text",
        success : function (data) {
            if(data === '*'){...}
        }
    });
}); 

But even if you change to this, you won't get results from a localdrive, you'll need an actual http server to serve the static textfile. Please check the network requests and update here what response you get.