JSFiddle - React, Tailwind, and code Playground

HTML

<input type="checkbox" value="">Select All<br/>
<input type="checkbox" value="">A<br/>
<input type="checkbox" value="">B<br/>
<input type="checkbox" value="">C<br/>
<input type="checkbox" value="">D<br/>
<input type="checkbox" value="">E<br/> 
<input type="checkbox" value="">F<br/>
<input type="checkbox" value="">G<br/>
<input type="checkbox" value="">H<br/>
    
    <script>
        var inputs = document.querySelectorAll('input[type=checkbox]')
        Object.keys(inputs).forEach(function(i){
            inputs[i].checked = true
        })
    </script>