Untitled

<!DOCTYPE html>
<html lang="en">

<head>
  <title>Get Nearest word of cursor</title>
</head>

<body>
  <input id="textArea" type="text"/>
<br />
<input id="Submit" type="submit" value="Test" onclick="getPreviousWordOfCursor()"/>

<script>

  function getPreviousWordOfCursor() {
    var textElement = document.getElementById('textArea')
    let caretPos = 0
        if (document.selection) {
            textElement.focus()
            let Sel = document.selection.createRange()
            Sel.moveStart('character', -textElement.value.length)
            caretPos = Sel.text.length
        } else if (textElement.selectionStart || textElement.selectionStart == '0') {
            caretPos = textElement.selectionStart
        }
        let text = textElement.value
        let preText = text.substring(0, caretPos)
        let resultWord
        if (preText.indexOf(" ") > 0) {
            let words = preText.split(" ")
            resultWord = words[words.length - 1]
        }
        else {
            resultWord = preText
        }
      alert(resultWord)
  }

</script>

</body>

</html>