index === 0 are false, index == 0 are true

[sn01615]

{@each carousels as it, index}
  {@if it.carousel_location==1}
    <div class="item{@if index === 0} active{@/if}">
      <a href="{@if it.carousel_pid > 0}${baseurl}app/item?pid=${it.carousel_pid}{@else}${it.carousel_link}{@/if}" class="carousel_warp"
      style="background-image: url(${it.carousel_img});"><!-- <img src="${it.carousel_img}"> --></a>
      <div class="carousel-caption">${it.carousel_text}</div>
    </div>
  {@/if}
{@/each}

${it.max_order?it.max_order:'9999999'} => ''
${it.max_order>0?it.max_order:'9999999'} => '9999999'