set disabled true javascript code example

Example 1: javascript disable button

//disable the button
document.getElementById(BUTTON_ID).disabled = true;
//reable the button
document.getElementById(BUTTON_ID).removeAttribute('disabled');

Example 2: howt to disable a select tag using js

document.getElementById("one").onchange = function () {
  document.getElementById("two").setAttribute("disabled", "disabled");
  if (this.value == 'car')
    document.getElementById("two").removeAttribute("disabled");
};