JSFiddle - React, Tailwind, and code Playground

HTML

<textarea id ="mytextarea"></textarea>
<div>
    
    the current word is <span id="current"></span>
</div>

JavaScript

$('#mytextarea').keyup(function(e) {
 if(e.keyCode === 37 || e.keyCode === 39) 
    {
       $("#current").text(getWord());
    }
});

function getWord()
{
    var sel, word = "";
    if (window.getSelection && (sel = window.getSelection()).modify) {
            var selectedRange = sel.getRangeAt(0);
            sel.collapseToStart();
            sel.modify("move", "backward", "word");
            sel.modify("extend", "forward", "word");
            
            word = sel.toString();
            // Restore selection
            sel.removeAllRanges();
            sel.addRange(selectedRange);
        } 
    else if ( (sel = document.selection) && sel.type != "Control"){  
            var range = sel.createRange();
            range.collapse(true);
            range.expand("word");
            word = range.text;
        }
        return word;
}