JSFiddle - React, Tailwind, and code Playground

HTML

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

JavaScript

arr = ['class="petname 1"> ','class="petname 2">', 'class="petname 3">'];
str = '<div id="idx">dsasdasd sd sad  dsad asds dasdas</div></div><div id="id1" class="petname 2">jkhda word2 jdslkajsldk........</div>';
num = arr.length;
 
for (var i=0;i<num;i++) {    
    found = str.match(arr[i]);
    if (found) {
       // ok, wir haben ein match , jetzt dein part......

       var ht_id_all_on1 = str.split(arr[i])[1];
       // alles hinter <div id="id1"  class="petname 2"> ausgeben
       $('#result').html(ht_id_all_on1);      
       
        //..........

    }
}