JSFiddle - React, Tailwind, and code Playground

HTML

<body>
    <table>
        <tr>
            <td>Hello there</td>
            <td id="HDD">I want to know this cell's color</td>
        </tr>
    </table>
</body>

CSS

TD {
	TEXT-ALIGN: CENTER;
	BORDER: 2PX SOLID BLACK; 
	BORDER-COLLAPSE: COLLAPSE; 
	BACKGROUND-COLOR: #D0A9F5; 
}
TABLE{
    BORDER-COLLAPSE: COLLAPSE;
}
}

JavaScript

//var myColor= document.getElementById("HDD").style.background="#D0A9F5"
//var myColor = document.getElementById("HDD").style.backgroundColor;
var Color = document.getElementById("HDD");

var myColor = window.getComputedStyle(Color,null).getPropertyValue('background-Color');
alert(myColor);