javascript - Bootstrap enable button on input -

i having issues getting done correctly. want "sendit" button enable (remove disable) there characters in box. i've tried multiple things can not work.

part of html:

<input type="password" id="inputpassword" class="form-control" placeholder="password" required>      <input id="sendit" class="btn btn-lg btn-primary btn-block disabled" type="submit" value="generate codes"></input> 

js file

    $(document).ready(function() {     var pass_error = 1;      // check name field          if (inputpassword === '') {             pass_error = 1;         } else {             pass_error = 0;         }         enablebutton();     });       // verzendknop pas activeren nadat alles ingevuld en gecontroleerd     function enablebutton() {         if (pass_error!== 0) {             $('#btn btn-lg btn-primary btn-block').attr('disabled', 'disabled');         } else {             $('#btn btn-lg btn-primary btn-block').removeattr('disabled');         }     }; }); 

your code checks field once upon dom ready.

you need tie check keyup event on field:

$('my-field').keyup(function() {  if($(this).val() === '') {   pass_error = 1; } else {   pass_error = 0;   enablebutton(); });