Still revealing both spoilers

$('.spoiler').on('click', 'button', function(event){
  console.log(event.target);
  // show the spoiler text
  $(event.target).prev().show();
  // hide the "reveal spoiler" button
  $(event.target).hide();
});

// create the "reveal spoiler" button
const $button = $('<button>Reveal Spoiler</button>');
// append to web page
$('.spoiler').prepend($button);

// hide spoiler on page load
$('.spoiler span').hide();

// when the button is pressed
$('.spoiler button').click(function(){
 // show the spoiler text
  $('.spoiler span').show();
  // hide the "reveal spoiler" button
  $('.spoiler button').hide();
});