JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://premium-api.com/jscourse/rb_plain.js"></script>
<span id='move'>Black</span>

JavaScript

// set base data
var isMoveBlack = true;
var gamePosition = "boooooooowoooooooowoooooowowboooooobwwwoooooowooooooooboooooowoo";

// define click function
function userClick(col, row) {
    console.log(col +"," + row);
    // TODO is move correct?
    var index = 8 * (row - 1) + col.charCodeAt(0) - 97;
    var cell = gamePosition.charAt(index);
    if ( cell == "o" ) {
        drawDisk(col, row, isMoveBlack);
        // TODO flip disks
        // save game position
        var disk = ( isMoveBlack ) ? "b" : "w";
        gamePosition = gamePosition.substr(0, index) + disk + gamePosition.substr(index+1);
        // change player
        isMoveBlack = !isMoveBlack;
    } else {
        alert('Wrong move!');
    }   
    
 if(isMoveBlack!=true){
document.getElementById('move').innerHTM='<p>White</p>';
}else{
document.getElementById('move').innerHTM='<p>Black</p>';
} 
    
}

// show current game position on the board
function drawAllDisks() {
    for (var i=0; i<gamePosition.length; i++) {
        var col = String.fromCharCode(97 + i % 8);
        var row = Math.floor(i / 8) + 1;
        var ch = gamePosition.charAt(i);
        if ( ch != 'o' ) {
            drawDisk(col, row, ch == 'b');
        }
    }
}

// draw board and start position
drawBoard(userClick);
drawAllDisks();