JSFiddle - React, Tailwind, and code Playground

HTML

<input type="checkbox"/>
<input type="checkbox"/>
<input type="checkbox"/>
<input type="checkbox"/>
<input type="checkbox"/>
<input type="checkbox"/>
<input type="checkbox"/>

JavaScript

[].forEach.call( document.querySelectorAll('input[type="checkbox"]'),function(el){
       el.checked=true;
     }
);