JSFiddle - React, Tailwind, and code Playground

HTML

<ul id="lines_list" class="foo bar foo-bar foo">
    <li>One</li>
    <li>Two</li>
    <li>Three</li>
</ul>

CSS

body {
    color: #0f0;
}

#foo {
    color: #f00;
}

JavaScript

alert( 'Before' + '\n' + document.getElementById( 'lines_list' ).className );

var ele = document.getElementById( 'lines_list' );
ele.className = ele.className.replace( /(?:^|\s)foo(?:\s|$)/gm, ' ' );

alert( 'After:' + '\n' + document.getElementById( 'lines_list' ).className );