JSFiddle - React, Tailwind, and code Playground

HTML

<table id="codexpl">
    <tr>
        <th>#</th>
        <th>Columna</th>
        <th>Relative</th>
        <th>Isso</th>
    </tr>
    <tr>
        <td id="0_0" onselectstart="onSelectStart(event);" onmousedown="onMouseDown(event)" onmouseover="onMouseOver(event)" onmouseup="onMouseUp(event)"><select>
  <option value="volvo">Volvo</option>
  <option value="saab">Saab</option>
  <option value="mercedes">Mercedes</option>
  <option value="audi">Audi</option>
</select></td>
        <td id="0_1" onselectstart="onSelectStart(event);" onmousedown="onMouseDown(event)" onmouseover="onMouseOver(event)" onmouseup="onMouseUp(event)">Test</td>
        <td id="0_2" onselectstart="onSelectStart(event);" onmousedown="onMouseDown(event)" onmouseover="onMouseOver(event)" onmouseup="onMouseUp(event)">Test</td>
        <td id="0_3" onselectstart="onSelectStart(event);" onmousedown="onMouseDown(event)" onmouseover="onMouseOver(event)" onmouseup="onMouseUp(event)">Test</td>
    </tr>
    <tr>
        <td id="1_1" onselectstart="onSelectStart(event);" onmousedown="onMouseDown(event)" onmouseover="onMouseOver(event)" onmouseup="onMouseUp(event)">Test</td>
        <td id="1_2" onselectstart="onSelectStart(event);" onmousedown="onMouseDown(event)" onmouseover="onMouseOver(event)" onmouseup="onMouseUp(event)">Test</td>
        <td id="1_3" onselectstart="onSelectStart(event);" onmousedown="onMouseDown(event)" onmouseover="onMouseOver(event)" onmouseup="onMouseUp(event)">Test</td>
        <td id="1_4" onselectstart="onSelectStart(event);" onmousedown="onMouseDown(event)" onmouseover="onMouseOver(event)" onmouseup="onMouseUp(event)">Test</td>
    </tr>
    <tr>
        <td id="2_1" onselectstart="onSelectStart(event);" onmousedown="onMouseDown(event)" onmouseover="onMouseOver(event)" onmouseup="onMouseUp(event)">Test</td>
        <td id="2_2" onselectstart="onSelectStart(event);" onmousedown="onMouseDown(event)" onmouseover="onMouseOver(event)" onmouseup="onMouseUp(event)">Test</td>
      ...

CSS

.selected{
  background-color: yellow;
}

JavaScript

var isMouseDown = false;

function onMouseDown(e) {
		isMouseDown = true;

     var cell = e.currentTarget;
		$('#codexpl').find(cell).addClass("selected");
    
    //e.preventDefault(); //to call only if user is selecting a range
    return false; // prevent text selection
};



function onSelectStart(e){
    e.preventDefault();
    return false;
};

function onMouseOver(e){
		if (!isMouseDown) return;
    
    var cell = e.currentTarget;
    $('#codexpl').find(cell).addClass("selected");
    e.preventDefault();
    return false;
}

function onMouseUp(e){
    isMouseDown = false;
}