how to figure out what word did someone meant javascript code example

Example: javascript Document word search and count

var input = document.getElementById('typed-text');

input.onkeydown = function (e) {

    if (e.keyCode === 13) {

        var paragraph = document.getElementById('paragraph');
        var result = document.querySelector('.result-output');
        var regexp = new RegExp(this.value, 'g');
        var textIncludes = paragraph.textContent.match(regexp);
            
        if (result)
            result.remove();

        paragraph.innerHTML = paragraph.textContent.replace(
            regexp,
            '<span style="color:red">' + this.value + '</span>');

        paragraph.insertAdjacentHTML(
            'afterend',
            '<span class="result-output" style="display: block; padding: 5px; margin-top: 10px; background: #eee; color: green;">' + (textIncludes ? textIncludes.length : 0) + ' words has been found.</span>');
            
    }

}
<div id="highlights">
        <div class="container">
            <div class="row">
                <div class="col-md-12" id="paragraph">
                    <p>
                       text
                    </p>
                </div>
                <div class="col-md-12 input-group mt-3">
                    <div class="input-group-prepend">
                        <span class="input-group-text" id="basic-addon1">
                            <i class="fas fa-pencil-alt"></i>
                        </span>
                    </div>
                    <input id="typed-text" type="text" class="form-control" placeholder="Type text">
                </div>
            </div>
        </div>
    </div>