JSFiddle - React, Tailwind, and code Playground

HTML

<form class="cart" action="https://dev.konsepta.no/eidehandel/catering/blamann/" method="post" enctype='multipart/form-data'>
		<div class=" product-addon product-addon-fisk">

	
			<h3 class="addon-name">Fisk </h3>
	
	
	
	<p class="form-row form-row-wide addon-wrap-4088-fisk-0-0">
		<label><input type="checkbox" class="addon addon-checkbox" id="rokelaks-m-eggerore-std" name="addon-4088-fisk-0[]" data-raw-price="28.00" data-price="28" value="rokelaks-m-eggerore-std"  /> Røkelaks m/eggerøre (std) (<span class="woocommerce-Price-amount amount"><span class="woocommerce-Price-currencySymbol">&#107;&#114;</span>&nbsp;28,00</span>)</label>
	</p>


	<p class="form-row form-row-wide addon-wrap-4088-fisk-0-1">
		<label><input type="checkbox" class="addon addon-checkbox" id="ekstra-eggerore" name="addon-4088-fisk-0[]" data-raw-price="12.00" data-price="12" value="ekstra-eggerore"  /> Ekstra eggerøre (<span class="woocommerce-Price-amount amount"><span class="woocommerce-Price-currencySymbol">&#107;&#114;</span>&nbsp;12,00</span>)</label>
	</p>


	<p class="form-row form-row-wide addon-wrap-4088-fisk-0-2">
		<label><input type="checkbox" class="addon addon-checkbox" id="cognacgravet-laks-m-sennepsaus-std" name="addon-4088-fisk-0[]" data-raw-price="17.80" data-price="17.8" value="cognacgravet-laks-m-sennepsaus-std"  /> Cognacgravet laks m/sennepsaus (std) (<span class="woocommerce-Price-amount amount"><span class="woocommerce-Price-currencySymbol">&#107;&#114;</span>&nbsp;17,80</span>)</label>
	</p>


	<p class="form-row form-row-wide addon-wrap-4088-fisk-0-3">
		<label><input type="checkbox" class="addon addon-checkbox" id="hel-kokt-orret-std" name="addon-4088-fisk-0[]" data-raw-price="16.60" data-price="16.6" value="hel-kokt-orret-std"  /> Hel kokt ørret (std) (<span class="woocommerce-Price-amount amount"><span class="woocommerce-Price-currencySymbol">&#107;&#114;</span>&nbsp;16,60</span>)</label>
	</p>


	<p class="form-row form-row-wide...

JavaScript

$(function check(){
   if (("div.product-addon").length > 0)
    {
     $("input[type='checkbox'][id$='std']").attr("checked", "checked");
    }
})