Javascript DOM oninvalid Event check input value length

Introduction

Alert some text if an input field contains less than 6 characters:

If you submit the form with less than 6 characters, an alert message will occur.

The oninvalid event is not supported in Internet Explorer 9 and earlier or Safari.

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<!DOCTYPE html>
<html>
<body>
<form action="/action_page.php" method="get">
  Name: <input type="text" id="myInput" name="fname" pattern=".{6,}" required>
  <input type="submit" value="Submit">
</form>/*  w  w w  . j  a v a  2  s . co  m*/
<p id="demo"></p>
<script>
document.getElementById("myInput").addEventListener("invalid", myFunction);
function myFunction() {
  document.getElementById("demo").innerHTML = "Must contain 6 or more characters";
}
</script>

</body>
</html>



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