JSFiddle - React, Tailwind, and code Playground

by Thiago Diniz

HTML

<li layout="0991a838-6ee1-453a-8569-ec75852f21a0" class="capacetes-de-moto--ls2-agv-norisk-shark-asw-mt-|-rs1">

  <div class="shelf-item-content" itemscope="" itemtype="http://schema.org/Product">
    <a href="http://www.rs1.com.br/capacete-norisk-ff391-squalo-preto-fosco-rosa/p" class="shelf-link in-stock text-center block" title="CAPACETE NORISK FF391 SQUALO PRETO FOSCO/ROSA" itemprop="url">
      <span class="shelf-discount block">9,53 %</span>

      <span class="shelf-image block">
			<span class="shelf-image-initial block" itemprop="image"><img src="http://rs1.vteximg.com.br/arquivos/ids/219479-260-260/CAPACETE-NORISK-FF391-SQUALO-PRETO-FOSCO-ROSA-4.png" alt="CAPACETE-NORISK-FF391-SQUALO-PRETO-FOSCO-ROSA-4" id="" width="260" height="260"></span>
      </span>

      <h3 class="shelf-name text-uppercase" itemprop="name">
			CAPACETE NORISK FF391 SQUALO PRETO FOSCO/ROSA
		</h3>
      <span class="shelf-price block" itemprop="offers" itemscope="" itemtype="http://schema.org/Offer">
									<span class="shelf-list-price block">
						<span>De: </span>
      <span>R$ 419,90</span>
      </span>
      Por: <span class="shelf-best-price" itemprop="price"> R$ 379,90</span> à vista

      <span class="shelf-installments block" itemprop="itemCondition">
											ou em até <span class="installment"> 8x </span> de <span class="installment-value"> R$ 47,48 </span> sem juros
      </span>
      </span>

      <span class="shelf-flags">
      
				<span class="shelf-flag-highlights">
          <p class="flag frete-gratis">Frete grátis</p>
          <p class="flag desconto-a-vista-5-">Desconto à vista 5%</p>
        </span>
        
        <span class="shelf-flag-discounts">
          <p class="flag desconto-a-vista-10-">Desconto à vista 10%</p>
        </span>
        
      </span>
    </a>
  </div>
</li>

<div id="result"></div>

JavaScript

$('.shelf-item-content:not(.formatted-price)').each(function() {
  var flag = [];
  var discountItem = $(this).find('.flag[class*="desconto-a-vista"]');
  
  if(discountItem.length > 1){
  	discountItem.each(function() {
    	var value = $(this).text().replace(/[^0-9]/g,'');      
      flag.push(value)      
     
    });
   
   var max = Math.max.apply(null, flag);
   
  }
  
  console.log(max)
 })