JSFiddle - React, Tailwind, and code Playground

HTML

<div contenteditable="true">
function(){<span class="newline"></span>
<span><pre>&#9;</pre></span>this.color=[12,23,34];<span class="newline"></span>
<span class="tab">&#9;</span>this.sayHello=function(){<span class="newline"></span>
<span class="tab">&#9;</span><span class="tab">&#9;</span>alert('hello');<span class="newline"></span>
<span class="tab">&#9;</span>}<span class="newline"></span>
}
</div>

CSS

.tab {
    white-space:pre;
}
.newline{
    display: block;
}