How to create a dropdown in UI Builder

In the UI there is element such as dropdown that appear when you click on any element - text, picture or icon - it can be anything. Dropdown is great if you need to give a user options with very little space, it can be very small and can pack a lot of information in a small space.
This recipe describes how to implement it in UI Builder.


Let’s start building dropdown by creating a component structure on the User Interface tab.
The general structure of the component is shown below. Each ID must be given a meaningful and unique name.
As a result, we will get a scheme like this (note : in the screenshot, the styles described below have already been applied):

For container , dropdown-container and dropdown, we will use the Block component.
Screenshot 2021-08-23 at 13.44.23

Use the Text component for dropdown target .

Screenshot 2021-08-23 at 13.44.29

Use any component that suits you to fill the dropdown block.

After adding content to our Block, let’s reset the styles using special button:

Screenshot 2021-08-23 at 17.25.18

It’s better to do this for each element to avoid unnecessary inline styles.


To create styles switch to the Theme tab. Inside the page, select the Editor and Extensions tabs.
Create an Extension. We recommend you name the extension according to the component name for convenience.
The following code is written using CSS LESS.

.container {
  margin: 0 10px;

.dropdown-container {
  align-items: center;
  position: relative;
  padding: 20px;
  &__text {
    text-decoration: underline;
    cursor: pointer;

.dropdown {
  position: absolute;
  visibility: hidden;
  opacity: 0;
  top: 70px;
  left: 20px;
  transition: all .3s ease-in-out;
  background: #e1f5f3;
  padding: 20px;
  box-shadow: 0 0 5px 2px rgb(0 0 0 / 5%);
  align-items: center;
  z-index: 2;
  width: 270px;
  justify-content: space-between;
  &.clicked {
    visibility: visible;
    top: 55px;
    opacity: 1;
    & ~ .dropdown-container__text {
      text-decoration: none;
  &::before {
    content: '';
    display: block;
    width: 10px;
    height: 10px;
    position: absolute;
    top: -10px;
    left: 0;
    border-left: 20px solid #e1f5f3;
    border-top: 10px solid transparent;


Below we show the logic for the appearance of the dropdown by clicking on the dropdown target element.
To do this, click on the element, then on the puzzle icon.
Then add the Codeless logic for adding and removing element classes on click.

Let’s walk through what this logic is doing:

  1. First, we have an “if” statement. The program looks at the classes for the element dropdown.
  2. If the assigned class is clicked, then the program performs the “do” portion of the if function. In that section, the program removes the class clicked, causing the dropdown to become inactive.
  3. If the assigned class is not clicked, then the program performs the “else” portion of the if function. There, it adds the class clicked to dropdown, making it visible.

Done! Now you know how to quickly and easily create a dropdown for your application using Backendless UI Builder.


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  1. The cryptic line “It’s better to do this for each element to avoid unnecessary inline styles.” refers to the three block components just installed.

  2. The ‘New Extension’ created refers to those three components; suggest using a name that relates to your working example.

  3. Before Preview, you must enter the three class names in the extension (‘container’, ‘dropdown-container’, ‘dropdown’) into the (respective) component ‘Classes’ setting.

Classes (example)

(Some of these notes are (at least alluded to) in “How To Add Customized Styles To Your App", pointed to in the Styles section.)

With these fixes, example works as shown.