JSFiddle - React, Tailwind, and code Playground

HTML

<span data-id="cast[]" class="label label-success label-as-badge custom-line-height">
<i class="glyphicon glyphicon-tag"></i>
     They Appear Here    
</span>
<span data-id="cast[]" class="label label-success label-as-badge custom-line-height">
<i class="glyphicon glyphicon-tag"></i>
     They Appear Here1    
</span>

JavaScript

var stringArr = $('span[data-id="cast[]"]').map(function(){
    return $(this).text().trim();
}).get();
alert(stringArr)