when i press Enter on the word counter not show the word

Codepen project link

How i change the regular Expression for count the word which anyone enter the write something on that

(countWords=()=>{
        s = document.getElementById("inputString").value;
        s = s.replace(/(^\s*)|(\s*$)/gi,"");
        s = s.replace(/[ ]{2,4}/gi," ");
        s = s.replace(/\n /,"\n");
        document.getElementById("wordcount").value = s.split(' ').length;

})()

<textarea name="inputString" id="inputString" cols="50" rows="4">Text to count</textarea>
<br>
<input type="button" name="Convert" value="Count Words" onClick="countWords();"> 
<input name="wordcount" id="wordcount" type="text" value="" size="6">