Set the maximum number of characters allowed in a password field:
document.getElementById("myPsw").maxLength = "10";
Click the button to set the maximum number of characters allowed in the password field.
<!DOCTYPE html> <html> <body> Password: <input type="password" id="myPsw"> <button onclick="myFunction()">Test</button> <p id="demo"></p> <script> function myFunction() {/*from www . j a va 2s. c om*/ document.getElementById("myPsw").maxLength = "10"; document.getElementById("demo").innerHTML = "Maximum number of characters allowed in the password field is now 10."; } </script> </body> </html>