JSFiddle - React, Tailwind, and code Playground

HTML

<!-- 原生JS -->

    <h1 class="title">
        Make me green
    </h1>

    <p class="para">
        Make me red
    </p>
    <p class="para">
        Me red too
    </p>
    <p class="para">
        Also me
    </p>

JavaScript

document.querySelector('.title').style.color = 'green';

for(var x of document.querySelectorAll('.para')){
    x.style.color = 'red';
}