How I can add and remove the attribute “readonly”?

Question

$(document).ready(function() {
  //Check City Value
  var city_value = parseInt($(\"#city\").val());
  if( city_value == 0) {
     $(\"#state\").attr(\"readonly\", true)         


        

Answer 1

You can do it in pure JavaScript (or Vanilla JS) without jQuery:

Set attribute readOnly:

document.getElementById("state").readOnly = true;

and unset:

document.getElementById("state").readOnly = false;

Equivalent to object-oriented notation is also this array-oriented notation:

document.getElementById("state")['readOnly']

It is also important that in JavaScript all the properties are case sensitive, so it is important to remember about the large O in the readOnly property, otherwise it will not work...