How to enable/disable button/dropdown using DOM/JavaScript.

One of the most and highly used DOM component is - "document".
In this example we are going to cover how to use the DOM object and we are going to disable/enable the HTML button and dropdown.
Let's write the sample HTML code which has the button and the dropdown element.


      <script src = "test.js"></script>
   <body style="background-color:#F2F2F2;">
      <button id="btn01">OK</button>
      <button onclick="disableElement()">Disable</button>
      <button onclick="enableElement()">Enable</button>
      <select id="mySelect">
      <input type="button" onclick="disable()" value="Disable list" />
      <input type="button" onclick="enable()" value="Enable list" />

Now that we are done with the sample HTML, let's write the JavaScript functions which will enable and disable the button and dropdown element.


function disableElement() {
    document.getElementById("btn01").value = "Disabled";
    document.getElementById("btn01").disabled = true;

function enableElement() {
    document.getElementById("btn01").value = "OK";
    document.getElementById("btn01").disabled = false;

function disable() {
    document.getElementById("mySelect").disabled = true;

function enable() {
    document.getElementById("mySelect").disabled = false;
The browser will render the above code something like this.


How to Confirm the password field using the JavaScript

In this example we are going to write a JavaScript code to make sure that the user is entering the password and confirm password fields equal to each other. First of all, we are going to design the UI using the standard html file.




function validate() {
    var password1 = document.getElementById("pass1");
    var password2 = document.getElementById("pass2");
    var msg = document.getElementById("message");
    var greenColor = "#66cc66";
    var redColor = "#ff6666";

    if (password1.value == password2.value) { = greenColor; = greenColor;
        msg.innerHTML = "Password is Matched!";
        return true;
    } else { = redColor; = redColor;
        msg.innerHTML = "Password do not match! Please try again.";
        return false;

      width: 100%;
    .tutorialWrapper form{
      background-color: #A9E2F3;
      border: 1px solid #cc9;
      padding: 10px;
      font-family: verdana;
      width: 75%;
      font-size: 1em;
      margin: 2px 0 2px 0;
      padding: 0;
    .tutorialWrapper label{
      float: left;
      text-align: right;
      margin: 0 5px 0 0;
      width: 30%;
    .tutorialWrapper input{
      width: 200px;
      border: 1px solid #cc9;
      margin: 0;
      padding: 0;
      font-size: .8em;


When Password and Confirm Password fields are equal then we will get the following result.

Until both the fields are not equal to each other it will keep displaying the below result.