[ruslan_mart]

.spolier:not(.spoiler-opened) .spolier_content {
    display: none;
}

<div class="spoiler">
    <div class="spoiler_title">SPOILER</div>
    <div class="spoiler_content">Content</div>
</div>

<div class="spoiler">
    <div class="spoiler_title">SPOILER</div>
    <div class="spoiler_content">Content</div>
</div>

<div class="spoiler">
    <div class="spoiler_title">SPOILER</div>
    <div class="spoiler_content">Content</div>
</div>

$('.spoiler_title').click(function() {
   $(this.parentNode).toggleClass('spoiler-opened');
});