title: 'IsNullOrWhitespace' in JavaScript?
body: <p>Is there a JavaScript equivalent to .NET's <a href="https://docs.microsoft.com/en-us/dotnet/api/system.string.isnullorwhitespace?view=netframework-4.7.2" rel="noreferrer"><code>String.IsNullOrWhitespace</code></a> so that I can check if a textbox on the client-side has any visible text in it?</p>
  
  <p>I'd rather do this on the client-side first than post back the textbox value and rely only on server-side validation, even though I will do that as well.</p>